Thesis (MSc(Agric))--University of Stellenbosch, 2005. / Bibliography. Also available via the Internet.

Thesis (MAgric)--University of Stellenbosch, 2007. / Bibliography. Also available via the Internet.

Thesis (MSc)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Grapevine is worldwide an agronomically important crop. Traditionally selective breeding has been used to improve existing cultivars. In the last ten years, however, the advent of biotechnology has shortened these breeding programmes by producing transgenic grapevine. Because this new technology is aimed at the possible genetic manipulation of the ripening process in grape berries, it is important to elucidate all the mechanisms that may be involved in ripening. The aim of the present study was the identification of genes that play an important role during the ripening process in grape berries. This was achieved by investigation of putative differentially expressed genes in ripening Chardonnay berries isolated through subtractive hybridisation. Two subtraction libraries, representing early and late ripening stages were constructed. Four of the ten genes analysed exhibited expression during berry ripening. One of the four genes was expressed in a tissue and stage specific manner. Further characterisation of eight of the DNA and protein sequences revealed that the putative translation products of these clones had homologues that are involved in amongst others cell wall structure in other species. These included UDP-glucose dehydrogenase, which is involved in the synthesis of hemicellulose precursors. The remaining seven clones encoded putative stress response proteins. These included two heat shock proteins, a vacuolar pyrophosphatase and a protein involved in cell division. It is suggested that specific grape mRNAs accumulate in response to stresses such as the storage of high concentrations of sugars and rapid cell expansion. These processes occur rapidly during the ripening of berries. Accumulation of specific mRNAs can be attributed to part of the normal ripening developmental programme. / AFRIKAANSE OPSOMMING: Druiwe is wêreldwyd 'n belangrike landbougewas en kultivars word tradisioneel deur middel van tydsame selektiewe teling verbeter. Die tyd wat hieraan bestee word, kan verkort word deur die implementering van biotegnologie en die produksie van transgeniese duiwe. Omdat hierdie nuwe tegnologie op die moontlike genetiese manipulering van die rypwordingsproses in druiwe gemik is, is dit belangrik dat alle meganismes betrokke by rypwording ondersoek en verstaan word. Die doel van hierdie studie was om gene wat moontlik tydens die rypwordingsproses in druiwe 'n rol kan speel, te identifiseer. Hierdie doel is bereik deurdat differensieel uitgedrukte gene uit die kultivar Chardonnay geïsoleer is met behulp van verrykingsbiblioteke vanuit jong en volwasse druiwekorrels. Vier van die tien gene wat geanaliseer is, word uitgedruk tydens die rypwordingsproses. Verder het een van die vier gene weefsel- en rypwordingstadium- spesifisiteit getoon. Volledige karakterisering van agt van die DNA- en proteïenvolgordes het aangedui dat die proteïenprodukte van hierdie gene homoloog is aan volgordes wat onder andere by selwandstruktuur betrokke is. Dit sluit UDP-glukose dehidrogenase in, wat betrokke is by die sintese van hemi-sellulose boustene. Die ander sewe gene kodeer vir moontlike spanningsproteïene. Twee hitteskokproteïene, 'n vakuolêre pirofosfatase en 'n proteïen wat betrokke is by selverdeling is geïdentifiseer. Daar word voorgestel dat druiwe mRNA versamel in reaksie op spanningsituasies soos die berging van hoë konsentrasies suikers en selvergroting. Hierdie prosesse vind baie vinnig plaas tydens rypwording. Versameling van spesifieke mRNAs kan toegeskryf word as 'n normale deel van die rypwordingsproses.

Call number: LD2668 .T4 1931 A51

Call number: LD2668 .T4 1933 B71

Call number: LD2668 .T4 1957 C46 / Master of Science

Thesis (PhD)--Stellenbosch University, 1981. / ENGLISH ABSTRACT: No abstract available / AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar

Spectrophotometric and chromatographic methods were employed to study the principal pigments in Evergreen blackberries and Alicante Bouschet grapes. Observations were made on the following items: 1. Juices expressed from the grape and blackberry 2. Principal pigments isolated from the grape and blackberry. 3. Wines made from the grape and blackberry. A Coleman Universal Spectrophotometer, Model No. 11, equipped with a single grating 35 millimicron fixed band, was used for the spectrophotometric study. Observations were made at the visible range of 400 millimicrons to 650 millimicrons at 50 millimicron intervals. Various concentrations of the juices, pigments, and wines were examined. The experiments were repeated with the samples made alkaline to pH 9 with sodium hydroxide. Blackberry wine mixed with 10, 20, 30, 40, and 50 per cent of grape wine were also examined in the sane manner. Results were shown graphically by plotting the E values against wave lengths. It was found that solutions of the higher concentrations always have the higher E values. In the spectrophotometric study, an absorption peak appeared at the 500 millimicron band in the blackberry juice which was not observed in the case of grape juice. The height of the peak was directly proportional to the concentration of the juice and it was unmeasurable when the juice was diluted to 5 per cent or lower. When the juices were made alkaline, all of them had the identical absorption curves except that the blackberry had its curves in higher positions than those of grape. Approximately twice the amount of anthocyanin pigments were isolated from the Evergreen blackberry than Alicante Bouschet grape. The principal pigments isolated from the blackberry were more intense in color than those from the grape. The isolated pigments of Evergreen blackberry and Alicante ouachet grape behaved similarly under the spectrophotometer, indicating that, qualitatively, the same pigments were obtained from blackberry and grape while using the same isolation procedure. Spectrophotometric study of the wines showed that the E values of blackberry wine were inversely proportional to the addition of grape wine. This appeared to be true in both acid and alkaline solutions. By adding 80 per cent of the alkali required to bring the wine to pH 9, more differences in E values between the various mixtures were observed. During the chromatographic atudy, using corn starch as adsorption material, a green band of approximately 1 cm deep was observed in the case of grape wine, which was absent in blackberry wine. The process of wine making changed the quality of pigments as demonstrated in the chromatographic adsorption tubes. The use of acid solution and alumina adsorption mixture as studied by Hamill and Simonds seems more promising than alkaline solution as used in the present study for the detection of in grape wine blackberry wine. / Graduation date: 1944

No description available.

Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Chemistry in the Faculty of Applied Sciences at the Cape Peninsula University of Technology / This study sought to prepare and characterise activated carbons from Vitis vinifera (grape) leaf litter, and assess the efficiency and potential application of the adsorbent for the removal of four phenolic compounds (phenol (P), 2-nitrophenol (2-NP), 4-nitrophenol (4-NP) and 2-chlorophenol (2-CP)) from synthetic and industrial wastewaters. Vitis vinifera (grape) leaf litter (GL) was obtained locally, and washed, dried and pulvirized. Chemically activated carbons were prepared using H3PO4 (GLA) and NaOH (GLB). The adsorbents were characterized with SEM, FTIR, EDX and proximate analysis was also carried out. Phenols were extracted from water samples with SPE and analysed with HPLC. The prepared adsorbents were used in sorption of phenols from simulated phenolic wastewaters for optimization of adsorption. Optimal adsorption conditions were then applied for removal of phenols from wastewater samples collected from influents of treatment plants. Column and desorption studies were also carried out. The surface texture and morphology micrographs (using SEM) of the prepared materials/adsorbents showed that the prepared activated carbons possess improved pore structure, cavities and heterogeneous irregular surfaces capable of providing enhanced adsorption. EDX spectroscopy was used for elemental microanalysis and showed that the major constituent of the adsorbent is carbon. FTIR analysis revealed changes and absorption waveband drifts of surface functional groups after activation and adsorption. The proximate analysis of the prepared precursors demonstrated good quality of the active carbons. They had low moisture content (< 12%) and their inorganic matter content (ash) was less than 9% for the three sorbents. Iodine number value of the adsorbents was 342, 1065, and 571 mg/g for GL, GLA and GLB respectively. Excellent recoveries (92.60 – 102.85%) were obtained for the phenolic compounds (P, 2-NP, 4-NP and 2-CP) using polymeric SPE cartridges. Phosphoric acid activation yielded the most efficient activated carbon material relative to the non-treated biomass and those chemically activated with NaOH. Percentage removal was 92.70%, 99.92%, 99.98% and 99.90% for P, 2-NP, 4-NP and 2-CP respectively using GLA. Optimal pH for adsorption was 8, 4 and 7 for GLA, GLB and GL respectively at an equilibration time of 240 min. The evaluation of adsorption kinetics showed the adsorption process of GLA and GLB followed a pseudo-second order kinetic model while adsorption using GL was best described by intraparticle diffusion model. Adsorption equilibrium data were well fitted with Freundlich isotherm model for all three adsorbents. Adsorption capacity of GLA (for removal of phenols) was found to decrease with increase in temperature. In contrast, the sorption efficiency of GL and GLB increased when temperature was increased. Thermodynamic parameters of adsorption (ΔGo, ΔHo & ΔSo) were evaluated. Results revealed favourability and exothermic nature of adsorption of the phenols using GLA. Adsorption processes using GLB and GL were spontaneous and endothermic. Vitis vinifera leaf litter yielded good activated carbons and was effective in remediation of P, 2-NP, 4-NP and 2-CP from contaminated wastewaters.