Thesis (MscAgric (Viticulture and Oenology))--Stellenbosch University, 2008. / The South African table grape industry is under great pressure to produce table grapes of the best quality for the export markets. Quality defects such as poor colour, inadequate berry firmness, browning and soft tissue breakdown cause great losses in export. The firmness of table grapes is one of the major factors determining the eating quality of grapes. Consumers prefer grapes with a firmer flesh above those with soft flesh. Firmer berries are commonly accepted to have better eating quality and longer cold storage capacity. Factors that promote and maintain berry firmness are only speculated about; therefore producers cannot effectively control the development of firmer berries by managerial practises or by applying specific sprays. The study was done on Redglobe and two Waltham Cross clones (the firmer Clone 8 and softer Clone 13). The aim of this study was two-fold. Firstly the cellular and ultracellular differences between the tissues of firm and soft berries were determined. The effect of gibberellic acid (GA3), synthetic cytokinin (CPPU) and bunch applied calcium sprays on the cellular and ultracellular structure of berry tissues were also under investigation. Secondly, the effects of GA3, CPPU and bunch directed calcium sprays on berry firmness, eating quality and storage capacity were determined. To determine the cellular and ultracelular structure of berry tissues, light microscope (LM) and transmission electron (TEM) studies were done. In order to investigate the effect of different sprays on berry firmness, 20 mg/L GA3 (GA3 treatment) was applied at 10mm average berry size; 20 mg/L GA3 plus 3 mg/L CPPU (CPPU treatment) was applied at 10 mm average berry size; and a mixture of 8 L/ha Stopit® and 5 L/ha Caltrac® (calcium treatment) was applied directly to the bunches every two weeks from berry set till veraison for the calcium treatments. The control received no plant bioregulators (PBR’s). The treatments were the same for both cultivars. Grapes were stored three weeks at 0 °C and one week at 10 °C after which it was evaluated for loose berries, botrytis infections, rachis browning and berry split. Afterwards it was tasted by an independent tasting panel. Firm berries were found to have an opaque coloured flesh while soft berries had a gel-like translucent flesh. For berries with normal firmness, the opaque flesh is limited to the outer mesocarp of the berry. Extremely firm berries’ whole mesocarp consisted of the opaque coloured flesh while soft berries’ mesocarp consisted of mostly the gel-like translucent flesh with, in some cases, a very thin layer of opaque flesh just under the skin. Berry firmness was not related to cell size as the cell size of the tissues in the firm and soft berries were identical. Cell shape seems to play an important role in berry firmness. The cells in the opaque coloured flesh of the outer mesocarp are more turgid and oval than those in the gel-like flesh of the inner mesocarp. Berry firmness is therefore determined by the thickness of the outer mesocarp with the opaque coloured flesh that contains turgid cells. The thickness of cell walls between the different tissues did not differ. There was however a difference between the cell contents and the plasmalemmas of the inner and outer mesocarp. The plasmalemma and tonoplast of the outer mesocarp cells was more intact than those of the inner mesocarp. The membranes in the inner mesocarp are more subtracted form the cell wall than in the outer mesocarp. Both the PBR’s and calcium treatments cause a delay in sugar accumulation in the case of Redglobe and Waltham Cross. The CPPU treatment results in significantly bigger and firmer berries for both cultivars. In the case of Redglobe, this treatment cause bigger cells in the outer mesocarp suggesting a correlation between berry firmness and cell size. In the case of Waltham Cross, however, cell size did not play a role in berry size and firmness; instead the rate of cell division earlier in berry development. The CPPU treatment was the only treatment that maintains berry firmness during cold storage for Redglobe while GA3 and CPPU did so in the case of Waltham Cross. PBR’s seems to have no effect on cell wall thickness. In the case of Redglobe, the calcium treatments resulted in significantly thinner cell walls, but this can not be explained. Calcium and GA3 treatments had a negative effect on grape quality after cold storage of both Redglobe and Waltham Cross. The Waltham Cross CPPU treatment results in better taste and colour as observed by the tasting panel, while in the case of Redglobe, the tasting panel preferred the control. It is found that the use of CPPU in combination with GA3 had the best effect on the eating quality, storage capacity, berry size and firmness. When a producer decides to use the CPPU treatment in order to improve berry firmness, he must realize that it can cause delayed ripening which can affect the export of the fruit.

Thesis (MScAgric (Viticulture and Oenology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The table grape industry employ a wide range of viticultural management practices in order to produce the high quality grapes demanded by the export market. A common contributor to degrading the quality of table grapes is the occurrence of berry split, which not only has an unattractive visual effect, but also increases the berries’ susceptibility to infection by spoilage organisms. A number of environmental conditions such as rainfall and humidity, and/or agricultural practices, such as irrigation, and high density canopies, can lead to higher plant cell water content. This in turn, can increase the potential of berry split to occur. To date, the main method of berry split prevention has been the management of plant water status by; (i) regulating irrigation withdrawal times, and (ii) covering of canopies if rainfall is predicted prior to harvest. The aim of this study was to determine the effect that irrigation frequency, as induced by irrigation withdrawals; as well as boron (B) and calcium (Ca) treatments, applied as bunch directed sprays, have on pre- and post-harvest berry split. To this end, a newly released late ripening, white seedless cultivar, SoutherngrapeOne was chosen as a model cultivar as it has a high susceptibility to berry split. SoutherngrapeOne vines were subsequently subjected to a range of irrigation frequencies based on typical irrigation scheduling used in the table grape industry, which comprised of a low, medium and high frequency. The low frequency was duplicated in order to demonstrate the effect that a heavy irrigation, just before harvest may have on berry split. These treatments were further subdivided to investigate the effect that B and Ca may have on berry split. For the B treatment, four Solubor1 bunch directed sprays were applied from 8mm berry size to véraison. The Ca treatment consisted of Stopit R 2 and Caltrac R 3 bunch directed sprays applied over the same period. In addition, a combination of the B and Ca treatment were applied to investigate any possible interaction. To account for the effect of water as solvent in the B and Ca treatments, and the spraying effect, pure water as treatment was also evaluated. Control vines received no sprays. The applied irrigation treatments resulted in different plant water status conditions. Separate applications of B and Ca treatments resulted in a decrease of B and Ca content in the flesh respectively. The control and combination treatment, of B and Ca resulted in the same of B and Ca content in the flesh. Furthermore, none of the applied treatments resulted in an increase of either B or Ca content in the berry skin. It was found that the medium frequency irrigation resulted in the best irrigation strategy to prevent pre-harvest berry split. Surprisingly, all the subtreatments: B, Ca, and combination of B and Ca, resulted in an increased incidence of pre-harvest berry split when compared to the control group for the 2006/07 season. However, in the 2007/08 season only the B treatment resulted in an increase of pre-harvest berry split. Concerning post-cold-storage physiological disorders, Ca treatments appear to have reduced berry drop, but increased decay. In the 2006/07 season, the B treatment resulted in reduced post-cold-storage berry split, whereas Btreatment in the 2007/08 season had no effect. Both B and Ca should be considered as having the potential to increase the appearance of hairline cracking. Calcium treatment also led to an increase in decay which may have been as a result of the splitting it contributed to. Low frequency irrigation recieving irrigation before harvest was found to result in browner stems. Low irrigation frequencies decreased the cell size of the berry skin. The Ca treatment gave rise to thicker (weaker) cell walls, this morphological change may be responsible for the physiological disorders it caused. From these findings, it can be deduced that poorly managed irrigation, together with unnecessary application of B and/or Ca may result in an increase of berry split and other physiological disorders, with subsequent financial losses for the producer. / AFRIKAANSE OPSOMMING; Die tafeldruifindustrie maak gebruik van ’n wye reeks wingerdkundige praktyke ten einde die hoë gehalte druiwe te produseer wat die uitvoermark vereis. Korrelbars is ’n algemene verskynsel wat afbreek maak tot die gehalte van tafeldruiwe. Behalwe dat voorkoms van die druiwe benaadeel word, verhoog dit ook in vatbaarheid vir infeksie deur verrottingsveroorsakende swamme. Hoë reënval en humiditeit, sowel as wingerdkundige praktyke soos besproeiing en hoë lowerdigtheid, wat kan lei tot verhoogde waterstatus in plante, kan lei tot ’n toename in korrelbars. Daar word hoofsaaklik van twee metodes gebruik gemaak om korrelbars te beheer, naamlik die bestuur van plantwaterstatus deur; (i) beheer van besproeiingsontrekkingstye en (ii) bedekking van lowers indien reën voorspel word voor oestyd. Die doel van hierdie studie was om vas te stel wat die invloed van besproeiings frekwensies sowel as trosgerigte boor (B) en kalsium (Ca), spuitbehandelings, op voor- en na-oes korrelbars het. Die onlangs vrygestelde laat rypwordende, wit, pitlose kultivar, SoutherngrapeOne is gebruik, aangesien dit hoogs gevoelig is vir korrelbars. Stokke is aan verskillende besproeiings intervalle, soos tipies gebruiklik in die tafeldruifindustrie, blootgestel. Hierdie intervalle bestaan uit n’ lae, medium en hoë besproeiings frekwensie. Die lae besproeiings frekwensie is herhaal ten einde die invloed van besproeiing net voor oestyd op korrelbars te ondersoek. Die invloed van B- en Ca-behandeling op korrelbars is ook ondersoek. Vir die B-behandeling is vier Solubor1 trosgerigte spuite aangewend vanaf 8mm korrelgrootte tot deurslaan. Vir die Ca-behandeling is Stopit R 2 en Caltrac R 3 as trosgerigte spuite oor dieselfde tyd toegedien. Kombinasiebehandelings is ook aangewend om enige interaksie tussen B en Ca te ondersoek. Waterbehandelings is ook toegedien om die invloed van water as oplosmiddel van B- en Ca-behandelings sowel as die spuit-effek te ondersoek. Kontrole stokke is ook ingesluit en het geen spuitebehandeling ontvang nie. Die besproeiingsbehandelings het verskillende plantwater toestande tot gevolg gehad, B- en Ca-behandelings het gelei tot ’n afname in B- en Cainhoud in die vleis onderskeidelik. Die kombinasie en kontrole behandelings het eenderse hoeveelhede B en Ca in die vleis tot gevolg gehad. Geen van die aangewende behandelings gelei tot ’n toename in B- en Ca-inhoud in die dop nie. Die resultate toon dat medium besproeiings frekwensie die beste besproeiingsstrategie is om voor-oes korrelbars te voorkom. In vergelyking met die kontrole-behandeling in 2006/07, het B, Ca en die kombinasie van B en Ca, ’n toename in voor-oes korrelbars tot gevolg gehad. In die 2007/08 seisoen het slegs die B-toediening egter tot ’n toename in voor-oes korrelbars gelei. Kalsium behandelings het ’n afname in los-korrels, maar ’n verhoging in korrelbars tot gevolg gehad. In 2006/07, het B-toediening tot ’n afname in korrelbars na koelopberging gelei, maar in die 2007/08 seisoen het dit geen effek gehad nie. Beide B- en Ca-toediening het die potensiaal om haarlyn barste te veroorsaak. Kalsium toediening het bederf verhoog wat moontlik aan die hoër bars wat dit induseer toegeskryf kan word. Lae besproeiings frekwensie, het bruiner stingels veroorsaak, en ook gelei tot ’n afname van selgrootte in die dop. Die Ca-toediening het aanleiding gegee tot dikker selwande in die dop. Hierdie anatomiese veranderinge kan moontlik die rede wees vir die verhoging in fisiologise afwykings. Van hierdie bevindinge kan ons aflei dat swak bestuur van besproeiing, sowel as die onnodige aanwending van B en/of Ca, kan aanleiding gee tot ’n toename in korrelbars en ander fisiologiese afwykings, en dus finansiële verliese vir die produsent inhou.

Thesis (PhD)--Stellenbosch University, 2002 / ENGLISH ABSTRACT: Prototypes of a new polymer S02 gas-generating sheet for the control of Botrytis cinerea during the post-harvest storage of table grapes, were developed and manufactured for evaluation using a pilot scale production plant. Attention was paid to the appearance of the sheet, in order to make it technologically efficient as well as aesthetically acceptable to both industry and consumers. The storage quality of semi-commercial export consignments of various cultivars table grapes packed with the monolithic thin-film polymer S02 slow release sheet, was evaluated and compared to results obtained using the locally manufactured Uvasys S02 sheet. The following were investigated: the efficacy of the new polymer sheets in controlling storage decay, the stage at which S02 damage is manifested on table grapes, the level of S02 damage associated with different S02 concentrations, whether S02 damage is manifested more readily at a particular position on the bunch, and the possible effect of an increase in storage temperature, from an initial storage at -O.5°C to 10°C, on the levels of S02 bleaching. Results showed that the new polymer S02 sheet compared favourably with the existing, commercially available Uvasys S02 sheets. The exact S02 concentration required for effective decay control varied for different cultivars, as well as for the different types of grape packages. The S02 concentration incorporated within the sheet was shown to be lower for grapes packed in non-perforated bags, and slightly higher for those in perforated bags. Differences between cultivars occurred with regard to the level of control and the levels of S02 damage. Levels of S02 damage were also significantly affected by the storage period and temperature fluctuations. No significant differences in the levels of decay development and S02 damage were observed in relation to the orientation of the bunches in the carton. The extent of damage incurred to grape tissue by the absorption of S02 gas was determined by low-temperature scanning (LTSEM) and transmission electron microscopy (TEM) techniques. LTSEM and TEM micrographs of areas damaged by S02 gas revealed that exposure to S02 gas may lead to plasmolysis and the loss of cellular fluids. Although damage to the cell walls, cell wall structures and cell membranes, caused by S02 gas, was more prominent in the tissue layers nearer to the fruit surface, damage also occurred to a lesser extent in deeper tissue layers. S02 gas release-rate studies of polymer S02 sheets containing various concentrations Na2S205 revealed that levels of S02 gas emitted depended largely on the levels of Na2S205 incorporated into the sheets. Higher levels of S02 gas were released with the polymer sheets of higher concentrations Na2S205. The release curve for the commercial Uvasys S02 sheet was very different to that of the polymer sheets, with much higher levels of S02 gas emitted initially by the Uvasys S02 sheet compared to the polymer sheets, while the polymer sheets emitted low levels of S02 gas for longer periods compared to the Uvasys S02 sheet. The manufacturing process and the pilot scale production plant that was developed and constructed was successfully used to manufacture polymer S02 generating sheets that are technically sound and efficient, and aesthetically acceptable to industry. The efficacy of such sheets, regarding levels of decay control and S02 damage, was similar to that obtained with the presently available, commercially used Uvasys S02 sheet. / AFRIKAANSE OPSOMMING: 'n Nuwe polimeriese S02-gasvrystellingsvel vir die beheer van Botritis cinerea gedurende die na-oes opberging van tafeldruiwe is ontwikkel en vervaardig. 'n Nuwe loodsaanleg is spesiaal vir hierdie doel ontwerp en gebou. Aandag is geskenk aan die voorkoms van die velle aangesien dit belangrik is dat die nuwe velle beide tegnologies effektief en esteties aanvaarbaar moet wees vir die sagtevrugtebedryf en verbruikers. Die opbergingskwaliteit van semi-kommersiële uitvoerbesendings van verskeie kultivars tafeldruiwe, verpak met die nuwe monolitiese S02- gasvrystellingsvelle, is bepaal. Die volgende is ook bepaal: die effektiwiteit van die nuwe polimeriese velle, die stadium waarby S02-skade op die druiwe duidelik word, die vlak van S02-skade wat met verskillende konsentasies S02-gas geassosieer is, die moontlike invloed wat 'n toename in temperatuur (vanaf -0.5° tot 1DOC) op die verbleiking deur S02 sal hê, en of die S02-skade by voorkeur in 'n sekere posisie op die druiwe sal plaasvind. Die nuwe S02-vel het baie goed vergelyk met die kommersieël beskikbare Uvasys S02-vel. Die S02-konsentrasie benodig vir die effektiewe beheer van Botritis cinerea beskadiging het egter van kultivar tot kultivar verskil. Die keuse van die tipe verpakking, geperforeerd of ongeperforeerd, het ook 'n rol gespeel. Die konsentrasie S02-gas benodig vir effektiewe beheer was laer wanneer die druiwe in die nie-geperforeerde sakke verpak was. Vlakke van S02-skade is ook noemenswaardig beïnvloed deur die opbergingsperiode en variasies in temperatuur. Daar was geen duidelike verskil in die ontwikkeling van bederf en S02-skade ten opsigte van die posisie van die trosse in die karton nie. Die mate van S02-skade aan vrugweefsel is deur middel van laetemperatuurskandeerelektronmikroskopie (LTSEM) en transmissieelektronmikroskopie (TEM) bepaal. Daar is bevind dat die blootstelling aan S02 moontlik tot plasmolise en die uitlek van sellulêre vloeistof kon lei. Alhoewel S02-skade aan die selwande en membrane meer prominent in die weefsel naby die oppervlak van die vrug was, het skade ook in die onderliggende lae plaasgevind. Die vlakke van vrygestelde S02-gas het grootendeels afgehang van die konsentrasie natriummetabisulfiet in die velle. Die S02-vrystellingskurwe van die nuut ontwikkelde polimeriese S02-velle het baie verskil van dié van die Uvasys vel. Laasgenoemde lewer aanvanklik 'n hoë konsentrasie vrygestelde S02-gas vir 'n kort periode, gevolg deur baie lae S02 vlakke daarna, terwyl eersgenoemde 'n laer aanvanklike S02 vrystelling het, gevolg deur vergelykederwys hoër S02 konsentrasies daarna. Die ontwikkelde vervaardigingsproses en die loodsaanleg wat daaruit voortgevloei het is dus suksesvol aangewend om goeie polimeriese S02- vrystellingsvelle te vervaardig. Hierdie velle is tegnies effektief vir die beheer van Bofrifis cinerea gedurende die na-oes verpakking van tafeldruiwe en is esteties aanvaarbaar vir die Suid Afrikaanse sagtevrugtebedryf.

This report presents research into policy implications in the Hex River Valley in the Western Cape Province. The research aims to understand how key policy interventions introduced by the democratic national government have performed over the past 20 years in this specific geographic area. The policy examined relate specifically to of agriculture, labour, housing, land reform, black economic empowerment, and substance abuse. The findings show mixed results. Some policy has gone a long way in improving the lives of people in the valley. In other instances it has been woefully inadequate. Often, policy is simply unable to keep up with the changing landscape and the new problems that continue to develop. All the while the table grape industry at the heart of this settlement has proved to be incredibly flexible in adapting. This report consists of two sections. The first is a long-form journalistic piece presenting the research and its findings in a narrative writing style which is intended to engage the reader. The second section is the scholarly methods document sets out the academic research supporting this work. It also analyses on the manner in which the research was conducted and the reasons therefore. / GR2017

Thesis (MSc (Genetics))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: South Africa is regarded as one of the top wine producing countries in the world. One of the threats to the sustainability of the wine industry is viral diseases of which Grapevine leafroll-associated virus 3 (GLRaV-3) and Grapevine virus A (GVA) are considered to be the most important and wide spread. Scion material is regularly tested for viruses; however scion material is often grafted onto rootstocks that have questionable phytosanitary status. Virus detection in rootstocks is challenging due to low and varying titres, but is imperative as a viral control mechanism. An additional viral control mechanism is the use of transgenic grapevine material which offers resistance to grapevine infection. The objective of this project was to establish a detection system using real time PCR (qPCR) techniques, to accurately and routinely detect GLRaV-3 and GVA in rootstock propagation material. qPCR would furthermore be used to perform molecular characterisation of transgenic plants containing a GLRaV-3 antiviral ΔHSP-Mut construct. A severely infected vineyard (Nietvoorbij farm) in the Stellenbosch area was screened throughout the grapevine growing season to investigate virus prevalence throughout the season and to determine the optimal time for sensitive virus detection. A large scale screening of nursery propagation material for GLRaV-3 infection was also conducted. The qRT-PCR results were compared to DAS-ELISA results to compare the efficacy and sensitivity of the two techniques. For the severely infected vineyard, the ability to detect GLRaV-3 increased as the season progressed towards winter. qRT-PCR was more sensitive and accurate in detecting GLRaV-3 than DASELISA, as the latter technique delivered numerous false positive results later in the season. The best time to screen for GLRaV-3 in the Western Cape region was from the end of July to September. For the nursery screenings, our qRT-PCR results were compared to the results of the DAS-ELISA performed by the specific nurseries. No GLRaV-3 infection was detected in the specific samples received from the two different nurseries. The results for all the samples correlated between the two techniques. This confirms that the propagation material of these nurseries has a healthy phytosanitary status with regards to GLRaV-3. However, the detection of GVA in the severely infected vineyard yielded inconsistent results. Detection ability fluctuated throughout the season and no specific trend in seasonal variation and virus titre fluctuation could be established. The highest percentage of GVA infected samples were detected during September, April and the end of July. Previously published universal primers were used for the detection of GVA, but further investigation indicated that they might not be suitable for sensitive detection of specific GVA variants present in South Africa. Vitis vinifera was transformed with a GLRaV-3 antiviral construct, ΔHSP-Mut. SYBR Green Real time PCR (qPCR) and qRT-PCR were utilised as alternative methods for molecular characterisation of transgenic plants. The qPCR and Southern blot results correlated for 76.5% of the samples. This illustrated the ability of qPCR to accurately estimate transgene copy numbers. Various samples were identified during qRT-PCR amplification that exhibited high mRNA expression levels of the transgene. These samples are ideal for further viral resistance studies. This study illustrated that the versatility of real time PCR renders it a valuable tool for accurate virus detection as well as copy number determination. / AFRIKAANSE OPSOMMING: Suid Afrika word geag as een van die top wyn produserende lande ter wereld. Die volhoubaarheid van die wynbedryf word onder andere bedreig deur virus-infeksies. Grapevine leafroll associated virus 3 (GLRaV-3) en Grapevine virus A (GVA) is van die mees belangrike virusse wat siektes veroorsaak in Suid-Afrikaanse wingerde. Wingerd bo-stok materiaal word gereeld getoets vir hierdie virusse, maar hierdie materiaal word meestal geënt op onderstokmateriaal waarvan die virus status onbekend is. Virus opsporing in onderstokke word egter gekompliseer deur baie lae en variërende virus konsentrasies, maar opsporing in voortplantingsmateriaal is ‘n noodsaaklike beheermeganisme vir virus-infeksie. Die doel van die projek was om ‘n opsporingsisteem te ontwikkel via kwantitatiewe PCR (qPCR) tegnieke vir akkurate en gereelde toetsing van GLRaV-3 en GVA in onderstokmateriaal. qPCR sal ook verder gebruik word vir molekulêre karakterisering van transgeniese plante wat ‘n GLRaV-3 antivirale ΔHSP-Mut konstruk bevat. ‘n Hoogs geïnfekteerde wingerd was regdeur die seisoen getoets om seisoenale fluktuasies in viruskonsentrasie te ondersoek en om die optimale tydstip vir sensitiewe virus opsporing te bepaal. ‘n Grootskaalse toetsing van kwekery voortplantingsmateriaal vir GLRaV-3 infeksie was ook uitgevoer. Die qRT-PCR resultate is met die DAS-ELISA resultate vergelyk om die effektiwiteit en sensitiwiteit van die twee tegnieke te vergelyk. Vir die hoogs geïnfekteerde wingerd het die GLRaV-3 opsporing toegeneem met die verloop van die seisoen tot en met winter. qRT-PCR was meer sensitief en akkuraat as DAS-ELISA in die opsporing van GLRaV-3, weens verskeie vals positiewe resultate wat later in die seisoen deur die laasgenoemde tegniek verkry is. Die beste tyd om vir GLRaV-3 te toets is vanaf einde Julie tot September. Tydens die kwekery toetsings was qRT-PCR resultate met die DAS-ELISA resultate van die spesifieke kwekerye vergelyk. Geen GLRaV-3 infeksie was waargeneem in die spesifieke monsters wat vanaf die kwekerye ontvang is nie. Die resultate van die twee tegnieke het ooreengestem vir al die monsters wat v getoets is. Dit het bevestig dat die voortplantingsmateriaal van hierdie kwekerye gesonde fitosanitêre status met betrekking tot GLRaV-3 gehad het. Die opsporing van GVA in die geïnfekteerde wingerd het egter wisselvallige resultate gelewer. Opsporing van die virus het ook regdeur die seisoen gefluktueer en geen spesifieke neiging in seisoenale opsporingsvermoë kon gemaak word nie. Die hoogste persentasie GVA geïnfekteerde monsters was waargeneem tydens September, April en die einde van Julie. Voorheen gepubliseerde universele inleiers was gebruik vir die opsporing van GVA, maar verdere ondersoeke het getoon dat hierdie inleiers nie noodwendig geskik is vir sensitiewe opsporing van GVA variante wat teenwoordig is in Suid-Afrika nie. Vitis vinifera was getransformeer met ‘n GLRaV-3 antivirale konstruct, ΔHSP-Mut. SYBR Green Real time PCR (qPCR) en qRT-PCR was ingespan as alternatiewe metodes vir molekulêre karaterisering van transgeniese plante. Die qPCR en Southern-klad resultate het ooreengestem vir 76.5% van die monsters. Dit illustreer die vermoë van qPCR om akkurate kopie-getalle van transgene te bepaal. Verskeie plante is geïdentifiseer tydens qRT-PCR amplifisering wat hoë vlakke van transgeen mRNA uitdrukking getoon het. Hierdie monsters is ideaal vir verdere virus weerstandbiedendheids studies. Hierdie studie het die veelsydigheid van real time PCR bewys en getoon dat dit ‘n kosbare tegniek is vir akkurate virus opsporing sowel as kopie-getal bepaling.

Thesis (MSc (Genetics))--Stellenbosch University, 2008. / The vine mealybug, Planococcus ficus (Signoret), is a severe pest of grapevine in many grape and wine producing countries around the world. It is renowned not only for the considerable damage it infers to grapevine of its own accord, but in particular for its role in transmitting deleterious viral diseases such as grapevine leafroll disease, Kober stem grooving, Shiraz disease and corky bark. Incidentally, it is an exceptionally tenacious antagonist of grapevine, being resistant to both chemical and biological control mechanisms. As a result, finding an effective strategy for P. ficus control has become a main priority of viticultural industries worldwide. Possible implementation of biotechnological approaches to pest management has resulted in a need for P. ficus genetic data - of which there are currently very little available. The transcribed genes of an organism can be captured in a cDNA library, and the sequences of the various transcripts can then be characterized. In this study altogether five cDNA libraries were constructed from the transcribed sequences of Planococcus ficus (Signoret). Instrumental to their construction was the identification of an RNA extraction protocol that provided large quantities of high quality RNA from mealybugs. The five cDNA libraries were the result of a set of modifications to the Creator™ SMART™ cDNA Library Construction Kit (used for Primary Library construction), and differed mainly with regards to range of insert sizes they contain. Whereas an abundance of short fragments were found in the Primary Library (42% of screened inserts 60.5 kb, and 20% >1 kb), the Fractionated Libraries contained inserts of specific size ranges that were more-or-less equally represented. The broadest size range was found in Fractionated Library 4, for which a uniform distribution over the range 0.25 kb - 4 kb was observed. Average insert sizes of Fractionated Libraries 1 to 4 were estimated at 0.25 kb, 0.5 kb, 1 kb and 2 kb respectively. These results demonstrated the importance of using a protocol designed to circumvent the bias towards incorporation of shorter transcripts in cDNA libraries. Although the libraries were not exhaustively analyzed, the outcome of a pilot investigation indicated that 41% of the submitted sequences had matches in the non-redundant database of the National Center for Biotechnology Information (NCBI, E-value 6 10-5), and that approximately 82% of these were of insect origin. Moreover, two potential targets for an RNAi-mediated approach to P. ficus pest control were identified. With one exception, these sequences seemed to be unique to arthropods. Future research needs to investigate the efficiency by which these sequences are able to constrain P. ficus proliferation, and their suitability for grapevine transformation.

Thesis (MScEng)-- Stellenbosch University, 2013. / ENGLISH ABSTRACT: South Africa is ranked as one of the largest table grape exporting countries in the world. The biggest markets for table grape exports have always been the EU and the UK, with emerging markets in Eastern Europe and Asia. The growing demand for pre-packaged fruit and vegetables in these markets are driven by factors like consumer comfort, hygiene and quality. These consumer needs have given rise to stringent quality control standards, putting more pressure on the producers to produce higher quality products. This thesis investigates the use of check weighing as a tool to enhance the operational effectiveness of table grape punnet packing. It looks at the current state of table grape punnet packing in South Africa, then determines the operational effectiveness of current packing practices and finally evaluates the merits of using automated check weighing as an operational management tool to improve current systems. Producers primarily make use of unskilled labour for the pre-packaging of table grapes, making it difficult to consistently produce good quality products. Some packing systems guide the operators towards filling punnets to the specified mass; some packing systems also feature internal check weighing in some form. Although these features improve mass accuracy and hence product quality, the packing processes are still prone to human and machine errors. Producers employ internal quality controllers who try to identify and rectify any human or machine errors as soon as possible. The PPECB, a local statutory body, enforces the minimum quality standards for South African exports by means of inspectors checking random product samples during production. If products of sub-standard quality are found (including under mass), the whole batch needs to be checked and repackaged where necessary, at great cost to the producer. Pre-packaged products may be produced according to the minimum mass system or the average mass system. The average mass system reduces the amount of raw product giveaway and increases revenue, but it requires that all products are check weighed and the masses recorded with a specified level of accuracy. The addition of automated final product check weighing saw a significant reduction in the occurrence of under as well as over mass punnets. It also managed to improve the productivity of some packing systems. Subsequent experiments with the check weigher using different setup parameters yielded much better measurement accuracy and would reduce under and over mass punnets even more. Considering the potential costs of having to repack batches due to the discovery of under mass products, it would be viable to implement automated final product check weighing even for small producers, with a payback period of less than 5 packing seasons depending on the producer’s specific pack house layout. The implementation of check weighing could not only reduce the risk of sub-quality products being produced, but also open up entirely new market opportunities in a very competitive market for products produced to the average mass system. / AFRIKAANSE OPSOMMING: Suid-Afrika is een van die grootste tafeldruiwe-uitvoerders ter wêreld. Die hoofmarkte vir tafeldruiwe-uitvoere was nog altyd die Europese Unie en Verenigde Koninkryk, met opkomende markte in Oos-Europa en Asië. Die groeiende behoefte vir voorafverpakte vrugte en groente in hierdie markte word gedryf deur verbruikersfaktore soos gemaksugtigheid, higiëne en kwaliteit. Hierdie behoeftes het tot gevolg gehad dat strenger reëls en regulasies vir kwaliteitsbeheer ontstaan het. Dit plaas ekstra druk op produsente om hoër gehalte produkte te produseer. Hierdie tesis ondersoek die gebruik van weging van die finale produk as ʼn hulpmiddel om die operasionele effektiwiteit van die verpakking van tafeldruiwe te verbeter. Daar word gekyk na die huidige toestand van die verpakking van tafeldruiwe in Suid-Afrika. Die operasionele effektiwiteit van bestaande verpakkingstelsels word bepaal. Die meriete van ʼn “weging van die finale produk stelsel” as bestuurshulpmiddel is nagevors. Daar word ook bespreek of die stelsel as bestuurshulpmiddel aangewend kan word om die effektiwiteit van huidige verpakkingstelsels te verbeter. Produsente maak primêr gebruik van ongeskoolde arbeid om tafeldruiwe te verpak. Dit maak dit moeilik om konstante goeie kwaliteit te lewer. Sommige verpakkingstelsels begelei die operateur om bakkies van ʼn spesifieke massa te produseer. Sommige verpakkingstelsels bevat ʼn interne toetsweeg funksie van een of ander aard. Alhoewel die funksies die akkuraatheid, produkmassa en dus produkkwaliteit verbeter, kan menslike- en masjienfoute steeds ʼn impak hê op die verpakkingsprosesse. Produsente maak gebruik van interne kwaliteitsbeheerstelsels wat poog om menslike- en masjienfoute so gou moontlik op te spoor en te herstel. Die PPECB, ʼn staatsliggaam, dwing die minimum Suid-Afrikaanse uitvoerstandaarde af deur middel van inspekteurs wat lukraak produkte tydens produksie ondersoek. Indien die produkte nie aan die kwaliteitstandaarde (insluitend massa) voldoen nie, moet die hele pallet nagegaan word en die bakkies moet reggemaak word waar nodig, teen ʼn groot onkoste vir die produsent. Voorafverpakte produkte kan volgens die minimum- of gemiddelde-massa sisteme geproduseer word. Die gemiddelde-massa sisteem verminder die hoeveelheid druiwe wat weggegee word en verhoog dus inkomste, maar dit vereis dat elke bakkie met ʼn bepaalde akkuraatheid geweeg moet word. Daar moet ook rekord gehou word van die massas. Die byvoeging van geoutomatiseerde finale produk toetsweging het ʼn aansienlike verbetering in die hoeveelheid oor- en ondermassa bakkies tot gevolg gehad. Dit het ook die produktiwiteit van party verpakkingsstelsels verbeter. Daaropvolgende weër eksperimente met ander opstellingsparameters het baie beter akkuraatheid getoon en dus kon die hoeveelheid oor- en ondermassa bakkies selfs verder beperk word. Met inagneming van die kostes daaraan verbonde om ʼn pallet oor te pak as gevolg van ondergewig bakkies, sou dit selfs vir klein produsente die moeite werd wees om finale produk toetsweging te implementeer. Dit het ʼn terugbetalingsperiode van minder as vyf pakseisoene, afhangend van die produsent se spesifieke pakstooruitleg. Nie alleen kan die implementering van finale produk toetsweging die risiko van ondergewig produkte verlaag nie, maar dit kan ook nuwe markgeleenthede oopmaak vir gemiddeldemassa produkte in ʼn baie kompeterende mark.

CAPES / A busca por produtos naturais e os riscos para a saúde decorrentes do consumo de antioxidantes sintéticos incentivam a investigação para a descoberta de novas fontes potenciais de compostos bioativos. A produção de vinho e suco de uva geram grandes quantidades de coprodutos ricos em compostos fenólicos que podem ser utilizados como antioxidantes naturais. Este estudo teve como objetivo avaliar as melhores condições de extração de compostos bioativos, através de um planejamento fatorial fracionário 24-1, de um coproduto oriundo do processamento da indústria de sucos de uvas (BUS – Bagaço de Uvas Suco) e de um coproduto oriundo do processamento da indústria de vinhos (BUV – Bagaço de Uvas Vinho). E, após a determinação da melhor condição para ambos os coprodutos, avaliar a atividade antioxidante utilizando diferentes metodologias de quantificação, sendo que dentre as duas amostras (BUS e BUV), a que obtivesse maior potencial antioxidante, seria testada no processamento de linguiça frescal de frango com intuito de verificar a inibição da formação de malonaldeído em comparação ao antioxidante sintético ES (eritorbato de sódio). Para a extração dos compostos bioativos as variáveis independentes estudadas foram: tipo de coproduto (BUS ou BUV), temperatura do banho-maria (40 ou 60 °C), tempo de extração dos compostos bioativos (15 ou 45 minutos) e o tipo de solvente utilizado (acetona 80% ou etanol 80%). Os extratos dos coprodutos foram analisados em termos do conteúdo total de compostos fenólicos por Folin-Ciocalteu e atividade sequestradora do radical DPPH• (variáveis dependentes). A atividade sequestradora de radicais livres nos 16 testes gerados variaram 65-149 μmol Trolox.g-¹ e compostos fenólicos totais entre 18-35 mg GAE.g-¹ (equivalente ácido gálico). A análise de regressão linear mostrou que mais de 97% da variabilidade dos dados foi explicada pelo modelo gerado para a variável dependente atividade antioxidante e 93% para compostos fenólicos totais. Levando-se em conta os pontos ótimos de extração para BUS e BUV, fixaram-se extrações com acetona 80%, 60°C, durante 15 minutos para BUS e 45 minutos para BUV. Sob essas condições de extração, BUS apresentou: atividade antioxidante pelo método DPPH (IC50), ABTS•+, FRAP, e percentual de inibição do sistema de β- caroteno/ácido linoleico em valores de 349 μg.mL-1, 334 mmol TEAC.g-1, 151 mmol Fe²+.g-1 e 73%, respectivamente. Enquanto BUV resultaram em 489 μg.mL-1, 249 umol TEAC.g-1, 111 umol Fe²+.g-1 e 68%, respectivamente. As respostas do planejamento fatorial mostraram que BUS teve o maior teor de compostos fenólicos e atividade antioxidante quando comparados ao BUV, em suas melhores condições. Foram elaboradas quatro formulações de linguiça frescal de carne de frango: amostra controle (sem antioxidantes – T1), amostra contendo antioxidante sintético a 0,01% (T2), amostra contendo 2 mg.g-1 de extrato de BUS (T3) e uma amostra contendo 4 mg.g-1 de BUS (T4). Para a elaboração das linguiças com extrato de BUS, utilizou-se o extrato da melhor condição, determinada pelo planejamento fatorial (acetona 80%, 60°C, 15 minutos), sendo que os extratos foram evaporados e liofilizados. Os parâmetros físico-químicos e microbiológicos das formulações T1, T2, T3 e T4, resultaram em valores que estão em concordância com as legislações vigentes. A cor sofreu variações durante o tempo de armazenamento das linguiças frescais de frango, sendo que T3 e T4 foram os tratamento que tiveram maior ΔE e menores valores de L*. Os tratamentos T1 e T2 obtiveram maiores valores de a*, b* e C*. O pH decaiu, para as quatro formulações de linguiças, variando de 6,71 a 5,99, entre os tratamentos. Para medir a oxidação lipídica foi utilizada a metodologia TBARS. As amostras contendo BUS foram capazes de inibir a oxidação lipídica. No tempo de 8 dias de armazenamento a 4°C, em relação ao controle, T2 conseguiu inibir a formação de malonaldeído em 0,31%, enquanto que os tratamentos contendo 2 e 4 mg.g-1 de extrato liofilizado de BUS (T3 e T4) inibiram 55% e 73% respectivamente. / The search for natural products and the risk to human health due to consumption of synthetic antioxidants encourage research for the discovery of new potential sources of bioactive compounds. The production of wine and grape juice generates large amounts of pomace rich in phenolic compounds that can be used as natural antioxidants. The objective of this work was to evaluate the extraction of bioactive compounds from pomace of grape juice (BUS) and wine (BUV) industry using a 24-1 fractional factorial design. After the determination of the better extraction condition for both co-products, was determinate with the total antioxidant activity using different determination methodology, and among the two samples (BUS and BUV), which obtained the largest quantifications by these methodologies, would be tested in the processing of chicken sausage in order to verify the inhibition of formation of malondialdehyde compared to synthetic antioxidant ES (sodium erythorbate)The independent variables studied were grape fruit pomace (GJP) and grape wine pomace (GWP), both temperature (40 and 60°C), extraction time of compounds (15- 45 min), and solvent type (acetone and ethanol, 80%). Co-products extracts were analyzed in terms of the contents of TPC by Folin Ciocalteu and scavenging activity of the DPPH• radical. After determining the best extraction method of bioactive compounds in each pomace (GJP and GWP), we determined the amount of antioxidants required to decrease the initial concentration of DPPH at 50% (IC50), ABTS• radical scavenging activity, Ferric Reducing Antioxidant Power (FRAP), and inhibition percentage by autoxidation of the system of β-carotene/linoleic acid. The DPPH radical scavenging activity in the 16 tests ranged from 65-149 μmol Trolox.g-1, and the TPC from 18-35 mg GAE.g-1 (gallic acid equivalent). The statistical analysis explains the significance of the effects and coefficients of the model generated in terms of their antioxidant activities. The linear regression analysis showed that the model generated explain more than 93% of the data variability. Thus, for both pomaces, acetone 80% was the best solvent for the extraction of antioxidant compounds and the ideal extraction temperature was 60°C. However, the best extraction time for GJP was 15 min and for GWP, 45 min. Under these extraction conditions, GJP showed activity in the DPPH method (EC50), ABTS•+, FRAP, and inhibition percentage at 339 μg.mL-1, 334 μmol TEAC.g-1, 151 μmol Fe2+.g-1and 73%, respectively. The values for GWP were 489 μg.mL-1, 249 μmol TEAC.g-1, 111 μmol Fe2+.g-1 and 68%, respectively. The responses of the factorial design showed that GJP had higher contents of phenolic compounds and antioxidant activity than GWP in its better extractions conditions. Was formulated four different chicken meat sausages: control sample (without antioxidant – T1), sample containing synthetic antioxidant 0.01% (T2), sample containing 2mg.g-1 of GJP extract (T3) and a sample containing 4 mg.g-1 of GJP extract (T4), the GJP extract was utilized lyophilized and in your optimized condition according to the factorial design (acetone 80%, 60ºC, 15 minutos), and the extracts were route-evaporated and lyophilized. The physicochemical and microbiological parameters of all formulations resulted in values that are consistent with current laws. Was observed color variations during the storage period of fresh chicken sausages, treatments T3 and T4 had the highest ΔE and the smaller L * values. T1 and T2 treatments had higher values of a *, b * and C *. The pH showed a reduction for the four formulations of sausages, ranging from 6.71 to 5.99, between treatments. To measure lipid oxidation TBARS methodology was used. Samples containing BUS were able to inhibit lipid oxidation. At time 8 days of storage at 4 ° C, compared to the control, T2 could inhibit the formation of malonaldehyde 0.31%, while the treatments with 2 ad 04 mg.g-1 of lyophilized BUS extract (T3 and T4) inhibited 55% and 73% respectively.

Thesis (MCom)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: “Within the context of the current market conditions, SCF may be one of the most attractive tools for companies to diversify funding basis, enrich and solidify their relationships with suppliers and their core banks.” – Michiel Steeman (Executive Director – Supply Chain Finance Community). (ING Group, 2013b). Insufficient cash flow is one of the major reasons for business failure in the current business environment. The spotlight is on collaboration between supply chain management and finance to release tied up cash in supply chains. Supply Chain Finance is a financial tool to help improve cash flow and optimise working capital to operate more efficiently. South Africa is one of the leading fruit exporters in the world with complex supply chains and even more complex financial arrangements. The need for Supply Chain Finance is aggravated by the long distances to overseas markets, and thus the long delay in payments after goods have been shipped. Supply Chain Finance is beneficial to the supplier, buyer and the financial service provider, creating a win-win-win situation. During this research the table grape export supply chain of Denau Farming is investigated to develop an explorative case study to implement Supply Chain Finance into their business model. During the research the problem of late payment received by buyers is explored by means of interviews and existing literature. A Concept Model is developed by adapting the Supply Chain Operations Reference Model (SCOR®) and the Management for Supply Chains (M4SC™) framework to identify the supply chain strategy during the current as-is physical and financial flow and to identify the gap in the supply chain. Two Supply Chain Finance solutions are identified based on Denau Farming’s financial needs in order to develop the to-be physical and financial supply chains and the resource changes required to facilitate the respective implementation. The final result determines how the proposed Supply Chain Finance solutions affect the expected cash-to-cash cycle time and the expected Economic Value Added (EVA®) in the case study. / AFRIKAANSE OPSOMMING: “Within the context of the current market conditions, SCF may be one of the most attractive tools for companies to diversify funding basis, enrich and solidify their relationships with suppliers and their core banks.” – Michiel Steeman (Executive Director – Supply Chain Finance Community). (ING Group, 2013b). Onvoldoende kontantvloei is een van die vernaamste redes waarom besighede in die huidige sakeomgewing misluk. Die kollig val op samewerking tussen voorsieningskettingbestuur en finansiering om kontant wat vasgevang is in voorsieningskettings te kan vrystel. Voorsieningsketting-finansiering is ‘n finansiële instrument wat kan help om kontantvloei verbeter en bedryfskapitaal te optimeer om meer doeltreffend te bedryf. Suid Afrika is een van die voorste vrugte-uitvoerders in die wêreld met komplekse voorsieningskettings en nog meer komplekse finansiële reëlings. Die behoefte vir voorsieningskettingbestuur-finansiering word vererger deur die lang afstande na oorsese markte, en dus die lang vertraging vir betaling nadat goedere reeds verskeep is. Voorsieningsketting-finansiering is voordelig vir die verskaffer, koper, en die finansiële diensverskaffer deur die skep van ‘n wen-wenwen situasie. As deel van hierdie navorsing is die tafeldruif-uitvoer voorsieningsketting van Denau Boerdery ondersoek as deel van die ontwikkeling van ‘n verkennende gevallestudie om sodoende voorsieningsketting-finansiering in hul sake-model te implementeer. Tydens die navorsing is die problem van laat betaling ontvang vanaf kopers in oorsese markte verder ondersoek deur middel van onderhoude en bestaande literatuur. ‘n Konsep model is ontwikkel deur die toepassing en aanpassing van die Supply Chain Operations Reference Model (SCOR®) en die Management for Supply Chains (M4SC™) raamwerk beginnende met die identifisering van ‘n voorsieningskettingstrategie tydens die huidige fisiese en finansiële vloei en die begin van ‘n gapings-identifisering vir die voorsieningsketting. Twee voorsieningsketting-finansiering oplossings is geidentifiseer gebaseer op Denau Boerdery se finansiële behoeftes en die ontwikkeling van ‘n verwagte toekomstige fisiese en finansiële voorsieningsketting asook die hulpbronveranderinge benodig wat die onderskeie implementerings kan help fasiliteer. Die finale navorsingsresultate bepaal tot watter mate die voorgestelde voorsieningsketting-finansiering oplossings die verwagte kontant-tot-kontant siklustyd asook die verwagte Ekonomiese Waarde Toevoeging (EVA®) in die gevallestudie beïnvloed.

Thesis (MSc)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: Thirty lactic acid bacteria were isolated from the intestinal tract of Drosophila simulans Stuvervant and nine lactic acid bacteria from Merlot grapes collected from the same winery in the Stellenbosch region, South Africa. The isolates were grouped according to morphological, biochemical and physiological characteristics. Isolates selected from each group were identified to species level by PCR with species-specific primers, PCR-based DGGE and 16S rDNA sequencing. The majority of isolates from the intestinal tract of Drosophila simulans Stuvervant belonged to the species Lactobacillus plantarum, but Lactobacillus paracasei, Lactobacillus sanfranciscensis, Leuconostoc mesenteroides subsp. mesenteroides, Lactococcus lactis subsp. lactis, Enterococcus faecalis and Pediococcus pentosaceus were also identified. As far as we could determine, this is the first report on the isolation of L. paracasei, L. sanfranciscensis, L. mesenteroides subsp. mesenteroides, L. lactis subsp. lactis, E. faecalis and P. pentosaceus from vinegar flies. Lactobacillus plantarum has previously been isolated from Merlot grapes. The genotypic relatedness among isolates of L. plantarum isolated from the intestinal tract of vinegar flies and from Merlot grapes were determined by RAPD-PCR. The isolates were grouped into four genotypically well-separated clusters. Thirteen isolates from grape must and five from flies yielded identical RAPD-PCR banding patterns and grouped into one cluster, suggesting that they are descendants from the same strain. This suggests that L. plantarum has the ability to use vinegar flies as a vector. / AFRIKAANSE OPSOMMING: Dertig melksuurbakterieë is vanuit die dermkanaal van Drosophila simulans Stuvervant geïsoleer en nege melksuurbakterieë vanuit Merlot-druiwe. Die druiwe is afkomstig van dieselfde wynkelder in die Stellenbosch-area van Suid-Afrika. Die isolate is volgens morfologiese, biochemiese en fisiologiese eienskappe gegroepeer. Verteenwoordigende isolate vanuit die fenotipiese groepe is tot spesievlak met behulp van lukraak ge-amplifiseerde polimorfe-DNA (RAPD) polimerase ketting-reaksie (PKR), PKR met spesie-spesifieke inleiers, PKR-gebaseerde denaturerende gradient-jel elektroforese (DGGE) en 16S rDNA sekwensering geïdentifiseer. Die meerderheid isolate uit die ingewande van Drosophila simulans Stuvervant is as Lactobacillus plantarum geklassifiseer. Stamme van Lactobacillus paracasei, Lactobacillus sanfranciscensis, Leuconostoc mesenteroides subsp. mesenteroides, Lactococcus lactis subsp. lactis, Enterococcus faecalis en Pediococcus pentosaceus is ook geïdentifiseer. Sover bekend, is dit die eerste keer dat L. paracasei, L. sanfranciscensis, L. mesenteroides subsp. mesenteroides, L. lactis subsp. lactis, E. faecalis en P. pentosaceus uit asynvlieë geïsoleer is. Lactobacillus plantarum is voorheen uit Merlot-druiwe geïsoleer. Die genotipiese ooreenkoms tussen die stamme van L. plantarum wat uit die asynvlieë en Merlot-druiwe geïsoleer is, is deur middel van RAPD-PKR bepaal. Hiervolgens is die stamme in vier genotipies goed-gedefinieerde groepe geplaas. Dertien isolate vanuit druiwemos en vyf vanuit asynvlieë het identiese RAPD-PKR bandpatrone vertoon en het in een groep gesorteer. Hierdie resultate dui daarop dat die stamme heel moontlik uit een voorouer ontstaan het en dat asynvlieë heel moontlik as vektor vir L. plantarum dien.