Thèses sur le sujet « Viticulture – South Africa – Robertson »

Thesis (MSc)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: The financial decision-making environment within which wine-grape producers function is challenging because of the complex interrelationships between yield, product price and input requirements. The complexity of farm systems is increased because production and financial decisions are necessarily made under uncertainty. Various issues influence the resilience of the wine industry. The goal of this study is to determine the financial implications of irrigation, integrated with canopy management practices on red wine cultivars in the Robertson area. Canopy management and irrigation cost play an important role within the multi-faceted farm system regarding yield, quality and input cost. This necessitates that research be carried out within the context of a systems approach. In this manner the interdependence among the various components of the farm system, and the associated synergies can be captured. Farm management, as a field of research, is dependent on other disciplines that present an alternative perspective to the research problem. Viticulture trials specifically focused on the impact of various irrigation and canopy management activities is being done on Wansbek farm. Nine treatments were tested at various combinations of soil water depletion levels and canopy management strategies. The farm is situated in Agterkliphoogte, an area in the Robertson valley. A multi-disciplinary group discussion was held to firstly obtain insight in the complex working of a farm. Secondly the group discussion was used to gain insight into the application of the Wansbek trial data and the setting of guidelines as to its application to determine the expected farm level financial implications of the treatments. Dealing with complexity necessitates insight form various areas of expertise, which is achieved time efficiently within expert group discussions. A quantitative method is required to reflect the interrelatedness and dynamics of a whole farm system in a user-friendly manner. Multi-period budget models present the ability to accommodate the complexity associated with a farm through a sequence of mathematical and accounting equations. The physical/biological interrelations and structure of the farm can be modelled while the financial performance of various irrigation and canopy management strategies can be determined. Farm-level profitability is especially sensitive to yield and price of farm products. The treatments that showed the highest expected profitability, return relatively high yields and prices at relatively low production costs. The sprawling canopy management treatment at c. 60% and c. 30% plant available water depletion levels returned the highest and second highest profitability at both gross margin per hectare and whole farm level. Scenarios were incorporated to illustrate the expected impact of key variables and the capability of the model. Key factors associated with the success of specific treatments could be identified. Results showed throughout that the balance between yield, price and input cost are the determining factor to profitability, rather than a focus on any particular one of these factors.
AFRIKAANSE OPSOMMING: Die finansiële besluitnemingsomgewing waarbinne wyndruifprodusente funksioneer, is uitdagend weens die komplekse verwantskappe tussen oesopbrengs en -kwaliteit en gepaardgaande insetbehoeftes. Die kompleksiteit van die boerderystelsels word verhoog deurdat produksie- en finansiële besluite noodwendig op grond van onvolmaakte inligting geneem word. Verskeie kwessies beïnvloed die voortbestaan van die wynbedryf. Die doel van hierdie studie is om die finansiële implikasies te bepaal van besproeiing, geïntegreer met lowerbestuur, vir rooi wyndruifverbouing in die Robertson-wynvallei. Lowerbestuur- en besproeiingkoste speel ʼn belangrike rol binne die multifasettigheid van ʼn boerderystelsel ten opsigte van opbrengs, kwaliteit en produksiekoste. Dit vereis dat die navorsing binne die konteks van die stelselsbenadering aangespreek word. Sodoende word die interafhanklikheid tussen die onderskeie boerderystelselkomponente, gekoppel aan die sinergistiese effek wat daarmee gepaardgaan, in ag geneem. Boerderybestuur as navorsingsveld, is gevolglik afhanklik van ander vakdissiplines wat ‘n alternatiewe perspektief verleen aan die navorsingsprobleem. Wingerdbouproewe wat spesifiek fokus op die impak van verskillende besproeiing- en lowerbestuursaksies word uitgevoer op die Wansbek-plaas. Die plaas is geleë te Agterkliphoogte, ʼn area in die Robertson-vallei. Nege behandelings is getoets teen verskillende kombinasies van plant beskikbare water (PBW)-onttrekkingspeile en lowerbestuurstrategieë. ʼn Groepsbespreking met multidissiplinêre deskundiges is gehou om eerstens, insig in die kompleksiteit van die werking van ʼn plaas te verkry. Tweedens, is die groep van multidissiplinêre deskundiges gebruik om insig te verwerf aangaande die hantering van die Wansbek-proefdata. Die groep het riglyne daargestel om die proefdata prakties aan te wend sodat die verwagte finansiële implikasies op plaasvlak geëvalueer kan word. Die hantering van kompleksiteit vereis insig vanuit verskeie gebiede van kundigheid wat tydsdoeltreffend binne ʼn groepsbespreking van multidissiplinêre deskundiges geakkommodeer kan word. ʼn Kwantitatiewe tegniek is nodig om die wisselwerking en dinamika van ʼn geheelboerderystelsel op ʼn gebruikersvriendelike en toepaslike manier te weerspieël. Multiperiode-begrotingsmodelle gee die vermoë om die kompleksiteit, wat met ʼn tipiese plaas geassosieer word, te akkommodeer deur die toepassing van basiese wiskundige en rekeningkundige beginsels. Die fisies-biologiese wisselwerking en struktuur van die plaas kan sodoende gemodelleer word, terwyl die finansiële prestasie van die kombinasies van verskillende besproeiing- en lowerbestuurstrategieë bepaal kan word. Die plaasvlakwinsgewendheid is veral sensitief vir die opbrengs en prys van produkte gelewer. Die behandelings wat die beste verwagte winsgewendheid getoon het, produseer teen ʼn relatiewe hoë produksie en prys en ’n relatiewe lae produksiekoste. Die oophanglowerbestuurbehandeling teen c. 60% en c. 30% plant beskikbare water-onttrekkingspeile is die mees en tweede mees winsgewende strategieë op per hektaar bruto marge en geheelplaasvlak. Die gebruik van scenario’s is geïnkorporeer om die impak van sleutelveranderlikes uit te wys en die vermoë van die model te illustreer. Sleutelfaktore tot die sukses wat aan sekere strategieë verbind word, kan sodoende uitgewys word. Deurgaans wys die resultate dat die balans tussen opbrengs, prys en produksiekoste belangriker is as die fokus op enige enkele een van die faktore.

Thesis (MScAgric (Viticulture and Oenology))--University of Stellenbosch, 2011.
Includes bibliography.
ABSTRACT: The grapevine must constantly find a balance between two continually changing environments, the rhizosphere (i.e. soil) and the troposphere (i.e. macroclimate). The adaptations are extremely complex because they encompass complicated and interrelated processes that are not yet fully understood. In terms of water-use behaviour, differences between cultivars have been described in the literature. In this study, the water status and stomatal conductance of four cultivars (Shiraz, Grenache, Pinot noir and Chardonnay) grafted onto R99 were studied. Diurnal cycles of water status and stomatal conductance, from 07:00 to 19:00, were followed for a single day at the end of the 2009 season. The results showed that, at the end of the season, Shiraz was subjected to water stress conditions, losing leaves and showing symptoms of berry shrivelling. The other three cultivars had a much better canopy status and no symptoms of berry shrivelling were observed. Based on the canopy observations and a comparison of the curves of stem water potential (Ψs) and stomatal conductance (gs), it seems that Pinot noir and Chardonnay are closer to the water-use behaviour of Grenache noir, which is known as a “pessimistic” cultivar, than to Shiraz, which is an “optimistic” cultivar. A study of four plots each of Chardonnay/101.14 Mgt and Shiraz/101.14 Mgt was carried out in eight commercial vineyards in the Robertson region in order to investigate the relationship between soil and root morphology, and the influence thereof on canopy development and berry growth. These plots had different soil types. Important soil properties are reported to limit root growth, individually or as a combination of restrictions. It was found that the size of the root system of 101.14 Mgt is defined by soil physical and chemical properties. The roots of 101.14 Mgt under irrigation can grow to a depth of 100 cm or beyond if the soil physical and chemical properties allow it. Because the soil properties define the root system and the water storage/drainage, they greatly influence the plant water status, even under irrigation. In an arid zone like Robertson, irrigation is an important management tool. The balance between canopy growth before véraison and the ability of the root-soil system to maintain that canopy size during the ripening process is crucial in an area with a high evaporative demand. In this regard, not all the soil properties-root system combinations showed satisfactory performance in maintaining the canopy functioning, which affected berry sugar loading and berry volume. In another study that is presented, forty soil profiles were characterised in the Robertson valley. The root systems were considered as a product of the soil properties, and thus the morphology of the root systems was used as a starting point to group soils together. The importance of soil depth has been described well, thus the root systems were first classified according to rooting depth – into shallow and deep root systems. The deep root systems were then subdivided, creating two subgroups of high root density and low root density. The two extreme groups (i.e. shallow roots, and deep roots with high root density) have particularly different soil properties. The soil characteristics found in these extremes are represented up to certain point by families of the South African soil taxonomy, mainly due to the restrictive function of the B horizon. This restrictive function is related to soil properties that are taken into consideration in the South African soil classification and that are important for grapevine root growth, as well as the thickness of the described horizons and the physical and chemical differences between the horizons. Soil properties have an important influence on root morphology. Due to the fundamental role played by the root system in the overall plant functioning, soil properties are of critical importance. In an arid area, the low water pressure in the atmosphere and the high temperature greatly affect the plant water status. The soil-root system combination plays an important role in the ability of the root system to supply the plant with water during times of high evaporative demand. Different cultivars will react differently due to differences in transpiration control. The maintenance of an adequate water status will have an immense influence on canopy development and maintenance, and on normal and steady berry ripening. In this study it was found that not all the soil-root combinations can fulfil this satisfactorily. Thus, the grapevine balance determined by the combination of the soil-root-canopy complex and the influence of management techniques is extremely important for the favouring of a good canopy:root system ratio, a functional canopy throughout the season and a steady berry ripening curve.

Thesis (MSc) -- Stellenbosch University, 2012.
ENGLISH ABSTRACT: One of the main objectives of the South African Wine of Origin Scheme (SAWOS) is to guarantee the quality of wine products emerging from South Africa’s viticultural production areas by preventing the abuse of names of products originating from outstanding viticultural areas. The study of terroirs contributes to knowledge that assists in delimiting potential viticultural areas in South Africa. Terroirs are areas with homogeneous groups of natural factors that, with the aid of effective management, have the potential to produce a unique product over a recognizable period. Natural terroir units (NTU) reflect the integration of relatively homogenous environmental factors, which include topography, climate, soil and geology. This study investigates the use of geographic information systems (GIS) and remote sensing methods in the identification of NTU in the Robertson wine district. Existing topographical, soil, geological and climatic GIS data layers were collected at various scales. In addition to this spatial data, orthorectified and radiometrically corrected SPOT 5 and ASTER satellite imagery were used to classify the land use/cover using an object-based image analysis (OBIA) approach. Eight land use/cover classes were distinguished by a sequential ruleset and an overall accuracy of 81.2% was achieved. The land use/cover layer was combined with the slope aspect and soil landscape to provide a three-component NTU description. One hundred and seventy NTU were identified, of which fifty five units exist for agriculture. These NTU can be used for site selection of agricultural produce and effective planning and management of land use. Climate was not included in the delimitation of NTU because the coarse resolution of climatic data could not be used to distinguish between different NTU. Therefore, all NTU identified in this research has similar climatic conditions. The major drawback of GIS-assisted terroir studies is the difficulty of representing a number of NTU on one GIS map. Therefore, it is recommended to associate the NTU map with a table of the classes instead. Furthermore, the accuracy, scale and resolution of available GIS data in South Africa influence the delimitation of NTU. Although remote sensing was found to provide efficient methods for land cover mapping, the use of multiseasonal satellite images would classify vineyards more efficiently because such an approach accounts for the different growth cycles of grapevines.
AFRIKAANSE OPSOMMING: Een van die hoof doelwitte van die Suid-Afrikaanse Wyn van Oorsprongskema (SAWOS) is om die kwaliteit van wynbouprodukte afkomstig van Suid-Afrikaanse wingerdbougebiede te verseker. Die studie van terroirs is geïdentifiseer as ‘n metode om moontlike wingerdbougebiede in Suid-Afrika af te baken. Terroirs is gebiede met relatief homogene natuurlike faktore wat oor ‘n erkenbare tydperk en met behulp van effektiewe bestuur die vermoë het om ‘n unieke produk te lewer. Dié natuurlike faktore word, “natuurlike terroir eenhede” (NTE) genoem en sluit topografie, klimaat, grond en geologie in. Hierdie navorsing ondersoek die gebruik van geografiese inligtingstelsels (GIS) en afstandswaarnemingstegnieke om NTE in die Robertson-wyndistrik te identifiseer. Bestaande ruimtelike topografiese-, grond-, geologiese- en klimaatdata is op ‘n verskeidenheid skale versamel. Bykomend tot hierdie ruimtelike data, is ortogekorrigeerde en radiometries-gekalibreerde SPOT 5 en ASTER satellietbeelde gebruik om landgebruik/ -bedekking te klassifiseer. Objekgerigte beeldanalise (OGBA) is toegepas tydens hierdie klassifikasie en agt landgebruik/ -bedekkingsklasse is onderskei deur gebruik te maak van ‘n stapsgewyse reëlstel. OGBA het ‘n algehele akkuraatheid van 81.2% gelewer. Die landgebruik/ -bedekkingsdata is gekombineer met hellingaspek en die grondlandskap om ‘n drieledige NTE-beskrywing te lewer. Een honderd en sewentig NTE is geïdentifiseer waarvan daar vyf-en-vyftig eenhede vir landbou bestaan. Hierdie NTE kan aangewend word vir die selektering van geskikte terreine vir landbou-gewasse en effektiewe grondgebruikbeplanning en -bestuur. As gevolg van die bestaande klimaatdata se growwe resolusie, was dit ongeskik om te onderskei tussen verskillende NTE. Dus heers daar soortgelyke klimaatstoestande vir elke NTE wat in hierdie navorsing geïdentifiseer is. Die grootste stremmende faktor wat GIS-verwante terroir navorsing beïnvloed, is die uitdaging om ‘n groot getal NTE op een kaart voor te stel. Daarom is dit beter om die NTE kaart met ‘n tabel te assosieer. Verder beïnvloed die akkuraatheid, skaal en resolusie van beskikbare digitale geografiese data in Suid-Afrika die afbakening van NTE. Alhoewel bevind is dat afstandwaarneming ‘n effektiewe metode is om landbedekking te karteer, sal die gebruik van meerseisoenale satellietbeelde wingerde meer doelmatig karteer omdat dit verskeie siklusse in die groei van wingerde in ag neem. SLEUTELWOORDE EN FRASES terroir, natuurlike terroir eenhede (NTE), geografiese inligtingstelsels, afstandwaarneming, wingerdkunde

Thesis (MScAgric (Soil Science))--University of Stellenbosch, 2011.
Includes bibliography.
ENGLISH ABSTRACT: The topic of landscape heterogeneity has captured the imagination of ecologists and agriculturists alike and has been extensively investigated in this dissertation. Heuweltjies are landscape features putatively created by the termite Microhodotermes viator through their burrowing and nest-building activities. They have been closely examined in the natural veld of the Western Cape in the recent past and are the focus of many ecological studies. However, the effect of heuweltjies in cultivated landscapes (e.g. vineyards, orchards and wheat lands) remains unexplored. This study contributes significantly to our understanding of soil modifications associated with heuweltjies, as well as the physiology of vines growing on and off heuweltjies and wine made from these vines. It was hypothesized that heuweltjies occurring in cultivated areas can significantly affect crop yield and quality, thereby establishing itself as a potentially important role player in the agricultural economy of the Western Cape. This study was conducted in two climatic regions of the Western Cape, Stellenbosch (Mediterranean climate, Cabernet Sauvignon) and Robertson (semi-arid climate, Shiraz) to better understand how differences in heuweltjie characteristics correspond to differences in rainfall and temperature. In both study areas, heuweltjie soils were compared to non-heuweltjie soils with respect to physical and chemical. Grapevines associated with these heuweltjies were also compared to those growing on the adjacent, non-heuweltjie soils to determine any variation in vine vigour, physiology, phenology, berry characteristics and wine quality. Through the use of ANOVA's and Fisher's LSD posthoc tests to indicate statistical significance in soil and grapevine characteristics, it was apparent that heuweltjies induce substantial changes in soil and vine properties. Significant differences in the water content exist between the soils of the heuweltjies and non-heuweltjie areas. Heuweltjie soils exhibited higher values in comparison to the non-heuweltjie soils in the Stellenbosch study area, with opposite results in Robertson. Heuweltjie soils also displayed higher exchangeable calcium and magnesium and higher total carbon and total nitrogen values than non-heuweltjie soils in both study areas. Differences in physiology were more subtle, but vine vigour was severely altered on the heuweltjie-associated vines, exhibiting excessive vegetative growth in Stellenbosch, leading to variations in berry characteristics on and off the heuweltjies. Again, the opposite was observed for Robertson. Lower sugar and alcohol percentages and higher titratable as well as malic acid concentrations were observed in the wines emanating from the heuweltjies in Stellenbosch. Sensory analyses proved significant, as lower astringency and alcohol burn were detected in the Cabernet Sauvignon heuweltjie wines than the non-heuweltjie wines in the Stellenbosch study area. Chemical differences in the wines from the Robertson study are were insignificant. However, a significantly lower fruitiness was observed in the Shiraz heuweltjie-wines when compared to the non-heuweltjie wines. Differences in soil water content between heuweltjies and its adjacent soils was the most influential factor in this study, and affected all of the soil-grapevine interactions to a large extent. Further research need to be conducted to better understand and clarify the reasons behind these variations, as well as possible effects of global warming on heuweltjie functioning in different climatic regions of the Western Cape.
AFRIKAANSE OPSOMMING: Die onderwerp van landskap heterogeniteit het die verbeelding van beide ekoloë en landboukundiges aangegryp en is op `n omvangryke wyse ondersoek in hierdie tesis. Heuweltjies is landskap eienskappe geskep deur die uitgrawe en nesbou aktiwiteite van die termiet Microhodotermes viator. Heuweltjies in die natuurlike veld is intensief bestudeer in die onlangse verlede en is die fokus van `n verskeidenheid ekologiese studies. In bewerkte landskappe (bv. wingerde, vrugteboorde en koringlande) is daar egter `n groot tekort aan navorsing oor die invloed van heuweltjies. Hierdie studie dra grotendeels by tot ons begrip van heuweltjie-geassosieërde grondverandering, asook die fisiologie van wingerd wat groei op en af van heuweltjies, sowel as die wyn afkomstig van hierdie wingerdstokke. Hipoteties sal heuweltjies in bewerkte areas die gewasopbrengs asook –kwaliteit betekenisvol beïnvloed en word so dus gevestig as `n potensieël belangrike rolspeler in die landbou-ekonomie van die Wes-Kaap. Die studie was onderneem in twee klimaatstreke van die Wes-Kaap, Stellenbosch (Mediterreënse klimaat, Cabernet Sauvignon) en Robertson (semi-ariede klimaat, Shiraz) om vas te stel hoe verskille in heuweltjie eienskappe ooreenstem met verksille in reënval en temperatuur. In beide studie areas is heuweltjie gronde met nie-heuweltjie gronde vergelyk met betrekking tot fisiese en chemiese eienskappe. Wingerdstokke geassosieër met heuweltjies is ook vergelyk met dié wat heuweltjies omring om enige variasie in groeikrag, fisiologie, fenologie, druifkorrel eienskappe en wynkwaliteit te bepaal. Deur gebruik te maak van ANOVA's en Fisher se LSD posthoc toetse om statistiese betekenisvolheid in grond- en wingerdeienskappe aan te dui, was dit duidelik dat heuweltjies wesenlike veranderinge in dié eienskappe teweegbring. Betekenisvolle verskille heers in die waterinhoud tussen die heuweltjie en nie-heuweltjie gronde. Heuweltjie gronde het hoër waardes getoon in vergelyking met die nie-heuweltjie gronde in die Stellenbosch studie area, met teenoorgestelde bevindings in Robertson. Heuweltjie gronde het ook `n hoër konsentrasie uitruilbare kalsium en magenesium, en totale koolstof en stikstof in vergelyking met nie-heuweltjie gronde. Verskille in fisiologie was baie meer subtiel, maar wingerd groeikrag was beduidend verskillend op die heuweltjie-geasossieërde wingerdstokke, met oormatige vegetatiewe groei in Stellenbosch wat lei tot `n verskil in druifkorrel eienskappe op en af van die heuweltjie. Weereens is die teenoorgestelde waargeneem in Robertson. Laer suiker en alkohol persentasies, asook hoër titreerbare - en appelsuur konsentrasies was te bespeur in die wyne afkomstig van die heuweltjies in Stellenbosch. Sensoriese analise het betekenisvolle verskille bewys, met `n laer vrankheid en alkohol-brand sensasie waargeneem vir die Cabernet Sauvignon heuweltjie wyne as die nie-heuweltjie wyne in die Stellenbosch studie area. Chemiese verskille in die wyne vanaf Robertson was onbeduidend. Sensoriese analise het egter anders bewys, met `n betekenisvolle laer vrugtigheid te bespeur in die nie-heuweltjie wyne as die heuweltjie wyne in die Robertson studie area. Verskille in die grondwaterinhoud tussen heuweltjies en omringende gronde was die mees invloedryke faktor in hierdie studie en beïnvloed tot `n groot mate al die grond-wingerdstok interaksies. Verdere navorsing is nodig om helderheid te verskaf agter die redes vir hierdie variasies, sowel as moontlike gevolge van aardverwarming op funksionering van heuweltjies in verskillende klimaatstreke van die Wes-Kaap.

MScAgric
ENGLISH ABSTRACT: The Little Karoo region of South Africa stretches from Montagu in the west, through Barrydale on the Langeberg Mountain, towards Ladismith, Calitzdorp, Oudtshoorn and De Rust in the east, with the Swartberg mountain range in the north. The Wine of Origin district of Calitzdorp is a small, demarcated area around Calitzdorp in the Little Karoo, surrounded by the Rooiberg, Swartberg and Kleinberg mountains. With a mean February temperature (MFT) of 23.7ºC and a low annual rainfall of 233 mm, the district of Calitzdorp has a similar climate to that of the Douro Demarcated Region (DDR). The MFT is comparable to the DDR mean July temperature, and it seems that the Douro Superior sub-region to the east of the DDR has a mean July temperature of higher than 25°C. In the Cima Corgo sub-region (in the centre of the DDR), and the Baixo Cargo sub-region, the mean July temperatures are ±25°C and ±22°C respectively. Annual rainfall in the DDR is much higher, with Baixo Cargo recording 1 018 mm, Cima Corgo recording 658 mm and Douro Superior in the east recording only 437 mm. Touriga Naçional is one of the highest quality Portuguese red grape varieties. It produces high-quality port-style wine as well as table wines. Excellent quality Touriga Naçional wines have a dark black/purple colour, good extract, high, elegant tannin content and intense aromas, with typical plum, raisin, wild fruit, mulberry, “fynbos” and cherry aromas. The most suitable terroir for Touriga Naçional in the DDR has been found to be on sites that restrain the natural vigour of the grapevine. Soils with moderate to low water-holding capacity, in association with low rainfall, result in water deficits during the growing season and are considered optimal to restrict growth vigour. A steep, northern middle slope is ideal in the southern hemisphere for high temperatures and sunlight interception. Warm temperatures (25 to 30 °C) during the day and cooler temperatures during the night are optimal for photosynthesis and colour development. In order to study factors affecting the quality of Touriga Naçional in Calitzdorp, two Vitis vinifera L. cv. Touriga Naçional commercial vineyards in the Calitzdorp district were selected. Each vineyard was divided into two separate management blocks based on their empirically determined quality of production. Two crop-reduction treatments, the standard 50% crop reduction (which was considered to be the control) and a further less drastic treatment of 25% crop reduction, were applied. Significant differences were found in viticultural performance between the two adjacent Touriga Naçional management blocks in each vineyard, especially with respect to vigour. The upper management blocks, which provided grapes for reserve-quality port-style wines, experienced a higher water deficit due to the moderate soil water-holding capacity and higher temperatures in comparison to the lower sites. The higher water deficits had a restraining effect on the Touriga Naçional vines, and therefore the upper sites had lower vigour, which contributed to better quality of both the wine and port-style wine, and this could be recognised sensorially. However, it was not reflected in the chemical analytical results. Crop load also appeared to have an effect on the Touriga Naçional grapevines, but this appeared to be dependent on the management block. The 50% crop reduction had a significant positive effect on the sensory analyses, but did not significantly affect the chemical analyses. Calitzdorp terroir has a similar effect on Touriga Naçional compared to the DDR terroir, and that is why Calitzdorp can produce good table and port-style wines from Touriga Naçional.
AFRIKAANSE OPSOMMING: Die Klein Karoo-streek in Suid Afrika strek vanaf Montagu in die weste, deur Barrydale teen die Langeberg, na Ladismith, Calitzdorp, Oudtshoorn en De Rust in die ooste, met die Swartberg in die noorde. Die distrik van Calitzdorp is ‘n klein area rondom Calitzdorp, in die Klein Karoo, wat deur die Rooiberg, Swartberg en Kleinberg omring is. Calitzdorp het ‘n gemiddelde Februarie-temperatuur (GFT) van 23.7°C en ‘n lae jaarlikse reënval van 223 mm, wat soortgelyk is aan die klimaat van die Douro Vallei in Portugal. Die Douro Vallei se gemiddelde Julie-temperatuur (GJT) in vergelyking met die GFT van Calitzdorp is hoër, met temperature van meer as 25°C in die substreek Douro Superior. Vir die substreke Cima Cargo en Baixo Cargo is die GJT ±25°C en ±22°C onderskeidelik. Die jaarlikse reënval is ook hoër by Baixo Cargo, met 1 018 mm, Cima Cargo met 658 mm en Douro Superior met slegs 437 mm. Touriga Naçional is een van die beste Portugese rooi kultivars wat hoëkwaliteit tafel- en portwyne produseer. ‘n Tipiese hoëkwaliteit Touriga Naçional-wyn het ‘n swartpers kleur, hoë ekstrak, hoë elegante tanniene en intense aromatiese geure wat tipiese pruim, rosyne, wilde vrugte, moerbei, fynbos en kersie aromas insluit. Die geskikste terroir vir Touriga Naçional is op swak gronde wat die natuurlike groeikrag van die wingerdstok strem. Gronde met matige tot lae grondwaterhouvermoë tesame met lae reënval veroorsaak ‘n waterstremming in die wingerdstok gedurende die groeiseisoen en word as optimaal beskou omdat dit beheersde groei veroorsaak. In die suidelike halfrond word relatief steil, noordelike middelhange as ideaal beskou vir hoë temperature en maksimale sonligonderskepping. Gepaardgaande hiermee is die interne dreinasie verantwoordelik vir vinniger uitdroging van die grond. Hoë temperature (25 tot 30°C) gedurende die dag en koue nagte is optimaal vir fotosintese en kleurontwikkeling. Twee Vitis vinifera L. cv. Touriga Naçional kommersiële wingerde in die Calitzdorp-distrik is geselekteer en in twee afsonderlike bewerkingsblokke verdeel, gebaseer op kwaliteitsverskille. In elke blok was die verdeling van so ‘n aard dat daar ‘n hoërliggende helfte en ‘n laerliggende helfte was. Twee trosverminderingsbehandelings, nl. 50% (kontrole) en 25%, gebaseer op trosgetalle, is toegepas. By elkeen van die wingerde was daar betekenisvolle groeiverskille tussen die twee aangrensende helftes. Die boonste helftes (of gedeeltes) het minder gegroei a.g.v. ‘n hoër waterstremming sowel as hoër temperatuur as die laer helftes. Dit het geblyk om ‘n positiewe invloed op die kwaliteit van beide die tafel- en portwyne uit te oefen. Troslading het ook ‘n effek op die Touriga Naçional-wingerde gehad, maar dit blyk of dit blok-afhanklik is. Die 50% trosverminderingsbehandeling het ‘n beduidende positiewe verskil in die sensoriese analises gemaak, maar nie ‘n beduidende verskil in die chemiese analises van die wyne nie. Calitzdorp se terroir het ‘n soortgelyke effek op Touriga Naçional as dié van die DDR terroir en daarom kan Calitzdorp soortgelyke goeie tafel- en portwyne van Touriga Naçional produseer.

Thesis (MScAgric) -- University of Stellenbosch, 2001.
ENGLISH ABSTRACT: There is an increasing demand by the consumer for knowledge and understanding of the origin of each wine produced. This origin is directly linked to the interaction between the environment and grapevine, and therefore to the terroir. A terroir can be defined as a complex of natural factors being expressed through the final product and must therefore be studied in two steps, namely, the identification of relatively homogenous natural terroir units followed by their ecophysiological characterisation. The aim of this study was to characterise the Bottelaryberg-Simonsberg-Helderberg wine growing area according to existing digital information and to identify natural terroir units. The study area is situated to the southwest of Stellenbosch and covers an area of approximately 25 000 ha. Topography is a static feature of the landscape and affects the sunlight interception by a slope, exposure of a site to winds and drainage of soil water and air. It forms an important component of the terroir concept and has a strong interaction with the environmental components of climate and soil. The study area is bordered by mountains and bisected by a river valley resulting in a large variation in aspect and altitude affecting both spatial and temporal temperature variability. There is no doubt as to the important effect of climate on wine character and quality. A number of indices can be used to describe the regional climate. The study area has a Mediterranean climate with notable spatial variation of all climatic parameters due to its complex topography and proximity to the ocean. The effect of geology on wme character is less clear but appears to act through its contribution to the physical properties of the soil. In the Bottelaryberg-Simonsberg- Helderberg study area the geology is complex due to the high degree of tectonic movement and mixing of parent material. In situ weathering of rocks is seldom the only source of soil formation. Soil has a number of contributing factors affecting wine character and quality, inter alia, soil colour, temperature, chemical composition, depth and texture (affecting the water supplying properties of the soil). It is the last two that appear to have the most significant effect. Soil depth affects the buffer capacity of the soil to temper climatic extremes and the water supply has a well-recorded effect on vine growth and functioning. There is a high degree of soil variation in the Bottelaryberg-Simonsberg-Helderberg study area that is difficult to represent in soil associations. A pattern of soil distribution, however, can be noticed in relation to landscape variation. Terrain morphological units, altitude and aspect were used as pnmary keys for the identification of natural terroir units. Broad soil categories and geological information were included at a secondary level. This resulted in 195 units. These natural terroir units will form the basis for future ecophysiological characterisation in order to determine possible future cultivar distribution as well as the terroir effect on wine character.
AFRIKAANSE OPSOMMING: Daar is toenemende aanvraag vanaf die verbruiker vir kennis en begrip van die oorsprong van elke wyn wat geproduseer word. Die oorsprong is direk aan die interaksie tussen die omgewing en wingerd gekoppel, en daarom ook die terroir. Terroir kan omskryf word as die kompleks van natuurlike faktore wat in die finale produk uitdrukking vind en studies daarvan moet dus in twee stappe plaasvind, d.i. die identifisering van relatiewe homogene natuurlike terroir eenhede gevolg deur die ekofisiologiese karakterisering daarvan. Die doel van die studie was om die Bottelaryberg-Simonsberg-Helderberg wynproduserende gebied te karakteriseer, met behulp van bestaande versyferde data en om natuurlike terroir eenhede te identifiseer. Topografie is 'n vaste landskapskenmerk en beïnvloed sonligonderskepping deur hellings, blootstelling van 'n ligging aan wind en die dreinerin~ van grondwater en beweging van koue lug. Dit is 'n belangrike deel van die terroir konsep en het sterk interaksie met omgewingsfaktore van grond en klimaat. Die studiegebied word begrens deur berge en is deursny deur 'n riviervallei, met groot variasie in helling en aspek. Beide hiervan beïnvloed die ruimtelike- en daaglik-variasies in daaglikse maksimum temperatuur. Die belangrike effek van klimaat op wynkarakter en kwaliteit is duidelik soos weerspieël deur die beskikbaarheid van 'n aantal makroklimaatsindekse. Alle klimaatsparameters word deur topografie beïnvloed. Temperatuur en relatiewe humiditeit word ook deur afstand vanaf die see beïnvloed. Die studie area het 'n Meditereense klimaat, met merkwaardige ruimtelike variasie van alle klimaatsparameters. Die effek van geologie op wynkarakter is minder duidelik, maar het waarskynlik 'n effek op die fisiese eienskappe van 'n grond. Die geologie in die Bottelaryberg-Simonsberg- Helderberg studiegebied is kompleks, as gevolg van die hoë graad van tektoniese beweging en vermenging van moedermateriaal. In situ vorming van gronde uit gesteentes vind selde plaas: Grond het 'n groot aantal bydraende faktore, wat wynkarakter en -kwaliteit kon beïnvloed, onder andere, grondkleur, -temperatuur, -chemiese samestelling, -diepte en -tekstuur (wat die waterleweringsvermoë van die grond bepaal). Dit is veral laasgenoemde twee faktore wat blykbaar die mees opvallendste effek openbaar. Gronddiepte bepaal die buffer kapasiteit van die grond om klimaatsuiterstes te kan weerstaan en die waterleweringsvermoë het 'n alombekende effek op wingerdgroei en funksionering. Daar is 'n hoë graad van grondvariasie in die Bottelaryberg-Simonsberg-Helderberg studiegebied wat moeilik is om met grondassosiasies weer te gee. Daar is wel 'n patroon van grond distribusie wat verband hou met landskapvariasie. Terrein morfologiese eenhede, hoogte en aspek is gebruik as primêre sleutels vir die indentifisering van natuurlike terroir eenhede. Globale grondkategorieë en geologiese inligting is op 'n sekondêre vlak gebruik. Dit het 195 eenhede tot gevolg. Die natuurlike terroir eenhede sal die basis vorm vir toekomstige ekofisiologiese karakterisering, om die terroir effek op wynkarakter te kan bepaal.

Thesis (MscAgric (Viticulture and Oenology))--University of Stellenbosch, 2009.
ENGLISH ABSTRACT: Little scientific information regarding the effect of different geological parent materials on grapevine performance is currently available in South Africa. This aspect is of special significance for the Helderberg area, where parent material may change from granite to shale over a short distance. This results in shale- as well as granite-derived soils often occurring within the same vineyard. The objectives of this study were to (i) quantify the nutritional status and other soil properties of different parent materials (shale and granite) and overlying soils (ii) investigate the impact of geological differences in the soil on the vine nutritional status and certain vine parameters. This study was done over two seasons (2006/2007 and 2007/2008). Two Sauvignon blanc and two Cabernet Sauvignon vineyard blocks were selected at two different localities for each cultivar in the Helderberg area, South Africa. Shale- and granitederived soils were identified within each block. Kaolinite was the dominant mineral, whereas quartz and feldspar were sub-dominant. Traces of mica were also present in some shale- and granite-derived soils. Granite- contained significantly higher contents of coarse sand than shale-derived soils, whilst the opposite occurred in terms of fine sand. These differences affected the water holding capacity, in general making it higher in shale- than granite-derived soils. Shale-derived soils had higher concentrations of total K but granite-derived soils had a higher ability to release K as they contained higher concentrations of soluble K. The Q/I parameters, potential buffering capacity of K (PBCK) and equilibrium activity ratio of K (ARK) showed no consistent responses to geological differences. Potassium concentrations were higher in the leaf blades (obtained before harvest in 2007) from Sauvignon blanc grapevines on granite- than on shale-derived soils. Potassium concentrations in the Cabernet Sauvignon juice (obtained in 2007) tended higher in juice from granite- than from shale-derived soils. In 2008, K concentrations tended higher in juice from shale- than from granite-derived soils for both cultivars. The pH of the Sauvignon blanc juice (obtained in 2008) tended higher in juice from shale-than from granite-derived soils, thus corresponding with the K concentrations in the juice in this season. Nitrogen concentrations were higher in Cabernet Sauvignon juice (obtained in 2007) and Sauvignon blanc juice (obtained in 2008) from shalethan from granite-derived soils. In terms of vine water status, vines on granite-derived soils appeared more stressed than those on shale-derived soils in both seasons at one of the vineyards. In these Sauvignon blanc and Cabernet Sauvignon vineyards, the K nutritional status was not affected by geology in a consistent manner but there were some noticeable tendencies for a specific cultivar during certain seasons. On account of vines being planted on shale- and granite-derived soils within the same block, soil preparation was done similarly for both soils, and they were exposed to similar irrigation schedules, canopy management strategies and climatic conditions. Therefore, there is a high probability that all these practices may have negated the effect of geology on the K status of soils and especially on juice K concentration at the time of harvest. It was clear that seasonal differences and fertilisation affected the nutritional status of the vines more than geology.
AFRIKAANSE OPSOMMING: In Suid-Afrika is daar tans min wetenskaplike inligting oor die effek van verskillende geologiese moedermateriale op die prestasie van wingerd beskikbaar. Hierdie aspek is veral van belang in die Helderberg-area, waar moedermateriaal oor ‘n baie kort afstand van graniet na skalie kan wissel. Dit lei daartoe dat skalie-, sowel as granietgronde, dikwels binne dieselfde wingerd voorkom. Die doelwitte van die studie was om: (i) die voedingstatus en ander grondkundige eienskappe van die verskillende moedermateriale (skalie en graniet) en oorliggende gronde te kwantifiseer (ii) die impak van geologiese verskille in die grond op wingerd se voedingstatus en sekere wingerdkundige parameters, te ondersoek. Hierdie studie is oor twee seisoene (2006/2007 en 2007/2008) gedoen. Twee Sauvignon blanc en twee Cabernet Sauvignon wingerdblokke is geselekteer by twee verskillende lokaliteite vir elke kultivar in die Helderbergarea, Suid-Afrika. Beide skalie- en granietgrond is binne elke blok geïdentifiseer. Kaoliniet was die dominante mineraal, met kwarts en veldspaat sub-dominant, terwyl spore van mika ook in beide skalie- en granietgronde gevind is. Granietgronde het betekenisvol hoër hoeveelhede growwe sand bevat, terwyl skaliegronde meer fyn sand bevat het. Hierdie verskille het ‘n effek op waterhouvermoë gehad en daartoe gelei dat waterinhoude oor die algemeen hoër was vir skaliegronde. Skaliegronde het groter hoeveelhede totale K bevat, maar granietgronde se vermoë om K vry te stel was hoër, omdat hulle ‘n hoër konsentrasie oplosbare K bevat het. Die Q/I parameters, potensiële buffervermoë vir K (PBCK) en ewewig aktiwiteitsverhouding vir K (ARK), is nie op ‘n konsekwente wyse deur geologiese verskille beïnvloed nie. Vir die Sauvignon blanc wingerde was kalium konsentrasies in blaarskywe (gemonster voor oes in 2007) hoër vir graniet- as vir skaliegronde. Kalium konsentrasies in die sap vanaf Cabernet Sauvignon (gemonster in 2007) het hoër geneig vir granietgronde. In 2008 het die kalium konsentrasies, vir beide kultivars, hoër geneig in sap vanaf skaliegronde. Gedurende dié seisoen het die pH van sap ook hoër geneig vir Sauvignon blanc vanaf skaliegronde, wat dus ooreenstem met die K inhoud van die sap. Stikstof konsentrasies was hoër in sap vanaf skaliegronde vir Cabernet Sauvignon (2007) en vir Sauvignon blanc (2008). In terme van die wingerde se waterstatus, het stokke op die granietgrond, by een van die lokaliteite, geneig om gedurende beide seisoene onder groter stremming te wees op graniet as op skaliegrond. In hierdie Sauvignon blanc en Cabernet Sauvignon wingerde, is K voedingstatus nie op ‘n konsekwente wyse deur geologie geaffekteer nie, maar gedurende sommige seisoene was daar wel duidelike tendense vir ‘n spesifieke kultivar. Omdat die stokke binne dieselfde blok op skalie- en graniet gronde geplant is, was grondvoorbereiding eenders vir die twee grondtipes terwyl besproeiingskedule, lowerbestuur en klimaatstoestande ook identies was. Daar is dus ‘n hoë waarskynlikheid dat al hierdie faktore daartoe kon bygedra het dat die effek van geologie op die K status van van gronde versluier is, veral die effek op die K inhoud van sap teen oestyd. Dit was duidelik dat seisoenale klimaatsverskile en bemestingspraktyke ’n groter effek as geologie op die voedingstatus van die wingerd gehad het.

Thesis (MScAgric) -- University of Stellenbosch, 2002.
ENGLISH ABSTRACT: The table grape industry is a major contributor to the South African economy, directly through foreign earnings from this predominantly export-based industry, as well as indirectly through the employment of thousands of people. It is a growing industry and consists of several production areas. The fastest growing table grape production area in South Africa is the Lower Orange River area, which produces some of the earliest grapes in the Southern Hemisphere. The biggest river in South Africa irrigates this area and it has an extreme climate characteristic of semi-desert areas. This area is considered to be optimal for the production of high quality, early, white seedless grapes. Previously, this area was predominantly planted to Sultanina vines for the purpose of raisin production. When seedless table grapes became a consumer preference, the producers very successfully converted their production practices to yield export quality seedless grapes from the established Sultanina vineyards. Extensive new plantings as well as re-plantings occurred in this area, also including newer cultivars from local and overseas breeding programmes. Being a viticultural and economical hot-spot, the Lower Orange River area is attracting much attention as a table grape production area and it also formed the backdrop to this study. The cultivar profile is changing in the area and it is projected that Sultana-, Regal-, Prime Seedless and Sugraone will be the four major early, white seedless cultivars in 2005. Based on this knowledge and prompted by a lack of information regarding production costs and general profitability of the new cultivars, this study was initiated in the form of a comparative analysis between the four mentioned cultivars spanning the early, middle and late regions of the Lower Orange River area. The approach used extracted information regarding cultural input costs (specifically labour as man-hours and the consequent costs) per manipulation performed in the vineyards. This approach is different from the more general method of obtaining input costs for a specific area based on combined mean values, often not distinguishing between cultivars. The specific aims of the study included a comparative analysis of input costs for production cultural practices per main manipulation action, as well as a comparative analysis taking into account productivity, value and extraordinary costs related to each of the four cultivars. To this end, 22 experimental plots were identified for use in the study. Collaboration of the production managers of each of the experimental plots were procured and information regarding production costs per manipulation and productivity of each cultivar and experimental plot were extracted from their own record keeping systems or from documents provided to the production managers. The value (price achieved) of the various cultivars for the 2001/2002 table grape season were put into perspective by using data from a survey which included information regarding payments for the various cultivars during the season in the Lower Orange River area. Information regarding fruit and vine royalties was obtained from the various plant breeders' rights holders of the various cultivars, where applicable. Primary descriptions of each experimental plot concerning general cultivation practices and information regarding the specific season were used to qualify results obtained from the various blocks. Several complicating factors impacted on the study and specifically the subsequent analyses of the results. Some of the factors were already identified as complicating factors in the planning stage of the study and were mostly linked to the recent introduction of two of the cultivars to the Orange River area. From the data gathered and the analyses performed it became clear that it would be difficult to discern significant differences (where significant is defined as PS0.10), but clear trends were observed and indications obtained. Based on the input cost analyses of this study it is proposed that mature Prime Seedless will have the highest labour input and cultural production cost of the four cultivars, followed by Sugraone. The labour input and the cost for the production cultural practices studied for young Prime Seedless vines were very high in comparison to the mature Sultana Seedless and Sugraone vines, especially for the canopy management and bunch manipulation actions. Prime Seedless was especially prone to the set of small and uneven berries, which lead to very high labour input requirements and subsequent cost for bunch manipulations. Sugraone is also known for the set of small and uneven berries in the Lower Orange River area, especially in difficult climatic seasons, also requiring high labour input for bunch manipulations. The initial indication is that mature Sultana- and Regal Seedless will require similar labour inputs for cultural production practices. The fact that Regal Seedless does not require expensive gibberellic acid (GA) applications, or girdling for thinning and berry enlargement purposes, is a tremendous advantage from a production cost point of view. Accordingly, initial indications are that Regal Seedless will have the lowest cultural production cost of the four cultivars. Regal Seedless was prone to the set of uneven berries during the year of study and accordingly it is suspected that this factor will ultimately determine the labour requirements and cultural production input cost, especially in difficult climatic seasons. The labour input and ultimately the cultural production cost for Sultana Seedless will be determined by the correct timing and concentration of the GA applications for thinning and berry sizing. Sultana Seedless and Sugraone produced high yields during the 2001/2002 table grape season in the Lower Orange River area. Yield information from the various experimental plots confirmed that there is little to choose between the two cultivars in terms of yield when cultivation conditions and practices are optimal. Large variation was observed in the yield results from the Regal- and Prime Seedless experimental plots. This is largely due to the recent introduction of the cultivars to the area and the consequent scarcity of blocks of these cultivars that are in full production. It was impossible to identify clear trends in terms of the future productivity of mature Regal- and Prime Seedless, but some indications of labour inputs could be extracted and qualified. Early maturing Prime Seedless and Sugraone performed very well in terms of price, especially in the harvest period prior to week 50. This advantage of high prices early in the season is, however, not always applicable to early cultivars in the later maturing regions of the Lower Orange River area. Later during the season, after week 50, when the supply of table grapes to the overseas markets has increased sharply, Sultana Seedless is usually the best performer in terms of price of the four cultivars. The ultimate price obtained by a cultivar is to a large extent determined by supply and demand, quality and acceptance of the specific cultivar. This study and its outcomes have a strong regional (Lower Orange River) and local (South Africa) impact and the specific results will undoubtedly be valuable to the producers, exporters and other role-players with vested interest in the cultivars studied or in table grape production per se. The methodology adopted in this study, however, is of broader interest and dearly shows the advantage of having detailed and qualified information regarding cultivation practices and bringing it in relation to the labour and consequent costs required per action. This should lead to more business intelligence and realistic planning on the producer side when decisions regarding the choice of a cultivar for a specific production area with a particular marketing scope have to be made. This study has also paved the way for similar studies, specifically with regard to the detailed description of the methodology that was established. Knowledge of the problems experienced in this study provides a useful reference for the planning and execution of similar studies.
AFRIKAANSE OPSOMMING: Die tafeldruifindustrie dra grootskaals by tot die Suid- Afrikaanse ekonomie: regstreeks deur middel van buitelandse valuta vanaf hierdie hoofsaaklik uitvoer-gebaseerde industrie, asook indirek deur werkverskaffing aan duisende mense. Dit is 'n vinnig groeiende industrie en bestaan uit verskeie produksie-areas waarvan die Benede-Oranjerivierarea, waar van die vroegste druiwe in die suidelike halfrond geproduseer word, tans die meeste groei toon. Die grootste rivier in Suid-Afrika vloei deur hierdie gebied wat deur uiterste klimaatstoestande, soortgelyk aan die van semi-woestyngebiede, gekenmerk word. Hierdie gebied is baie gunstig vir die produksie van hoë-gehalte, vroeë, wit pitlose druiwe. In die verlede is hoofsaaklik Sultanina vir die produksie van rosyne in hierdie gebied verbou. Namate pitlose tafeldruiwe voorkeur begin geniet het onder verbruikers wêreldwyd, het produseerders in die area hul verbouingspraktyke suksesvol aangepas vir die produksie van uitvoergehalte tafeldruiwe vanaf die grootskaalse, reeds gevestigde Sultanina-wingerde. Uitgebreide aanplantings en heraanplantings, wat nuwe cultivars van plaaslike en oorsese teelprogramme ingesluit het, is in hierdie gebied gedoen. Die vinnige groei in tafeldruifaanplantings en -uitvoere, asook die ekonomiese impak van die industrie in die Benede-Oranjeriviergebied, het die afgelope aantal jaar sterk op die voorgrond getree en het gevolglik gedien as agtergrond vir hierdie studie. Die cultivarprofiel in dié area is besig om te verander en volgens vooruitskattings gaan Sultana, Regal, Prime Seedless en Sugraone die vier prominente vroeë, wit, pitlose tafeldruifcultivars in 2005 wees. Gebaseer op hierdie feit en na aanleiding van 'n behoefte aan meer inligting met betrekking tot produksiekostes en algemene winsgewendheid van die nuwe cultivars, is 'n vergelykende studie aangaande die vier genoemde cultivars in die Benede-Oranjeriviergebied geloods. Die benadering wat gedurende die studie gevolg is, het inligting aangaande produksie-insetkoste (spesifiek arbeid in man-ure en gevolglike koste) per manipulasie onttrek. Hierdie benadering verskil van die meer algemene metodiek om insetkoste-inligting van 'n spesifieke area van gekombineerde gemiddelde waardes te verkry. Met so 'n benadering word gewoonlik geen onderskeid tussen cultivars getref nie. Die spesifieke doelwitte van hierdie studie het 'n vergelykende analise aangaande die insetkoste van die produksiepraktyke per hoofmanipulasie/aksie ingesluit, asook 'n analise waar produktiwiteit, waarde en buitengewone koste van die vier cultivars in ag geneem is. In totaal is 22 eksperimentele persele gebruik in die studie. Samewerking van die produksiebestuurders van die onderskeie esperimentele persele is verkry ten opsigte van die verskaffing van inligting oor produksiekoste per manipulasie, en die produktiwiteit per cultivar en eksperimentele perseel. Die produksiebestuurders het die nodige dokumente ontvang om die inligting te onttrek, of kon die inligting verskaf soos dit in hul rekordhoudingsisteem voorgekom het. Die waarde (prys behaal) van die onderskeie cultivars vir die 2001/2002-seisoen is in perspektief gestel deur gebruik te maak van 'n opname wat in die Benede Oranjeriviergebied plaasgevind het. Hierdie opname het inligting oor die uitbetalings van die onderskeie cultivars in die area vir die 2001/2002- seisoen ingesluit. Inligting rakende die stok- en vrugproduksie-tantieme is vanaf die onderskeie plantttelersregtehouers van die cultivars verkry. Primêre beskywings van die algemene verbouingspraktyke van elke eksperimentele blok en inligting oor die spesifieke seisoen is gebruik om die data wat vanaf die esperimentele persele verkry is, in perskektief te stel. Verskeie kompliserende faktore het die studie en die ontleding van data beïnvloed. Verskeie van hierdie faktore is reeds geidentifiseer met die beplanning van die studie en was meestal gekoppel aan die onlangse bekendstelling van Regal en Prime Seedless aan die Benede-Oranjeriviergebied. Na aanleiding van die data wat ingesamel en ontleed is, was dit duidelik dat dit moeilik sou wees om betekenisvolle verskille (waar "betekenisvol" as PS0.10 gedifinieer is) tussen die cultivars uit te lig, maar dat dit egter wel moontlik sou wees om aanvanklike indikasies en tendense te kry. Gebaseer op die insetkoste-ontleding van die studie blyk dit dat volwasse Prime Seedless die hoogste arbeidsinsetle en produksiekoste van die vier cultivars gaan hê, gevolg deur Sugraone. Die arbeidsinsetle en koste van die produksie-aksies wat van jong Prime Seedless bestudeer is, was baie hoog in vergelyking met volwasse Sultana Seedless- en Sugraone-stokke, veral ten opsigte van lowerbestuur en trosmanipulasies. Prime Seedless was veral geneig tot die set van klein, oneweredige korrels, wat tot baie hoë arbeidsinsetle en gevolglik koste vir trosmanipulasies gelei het. Sugraone is ook daarvoor bekend dat dit geneig is tot die set van klein, oneweredige korrels in die Benede-Oranjeriviergebied (veral in moeilike klimaatseisoene), wat gevolglik tot hoë arbeidsinstle vir trosmanipulasie lei. Die aanvanklike aanduiding is dat volwasse Sultana en Regal Seedless min of meer die dieselfde arbeidsinsetle vir verbouing sal vereis. Die feit dat Regal Seedless nie duur gibberelliensuur (GS)-behandelings vir blomtrosuitdunning of korrelvergroting benodig nie, is 'n enorme voordeel in terme van produksiekoste. Gevolglik is die aanvanklike aanduiding dat Regal Seedless die laagste produksieskoste van die vier cultivars sal hê. In die studiejaar was Regal Seedless egter geneig tot die set van onweredige korrels en gevolglik word verwag dat hierdie faktor uiteindelik die arbeidsinsetle en produsiekoste van die cultivar sal bepaal, veral in moeilike klimaatseisoene. Die arbiedsinsetle en produksiekoste van Sultana Seedless sal bepaal word deur die korrekte tydsberekening en konsentrasie van die GS-behandelings vir uitdunning en korrelvergroting. Sultana Seedless en Sugraone het gedurende die 2001/2002-seisoen hoë opbrengste in die Benede-Oranjeriviergebied geproduseer. Oesdata inligting van die onderskeie esperimentele persele het bevestig dat daar min te kies is tussen die twee cultivars in terme van produktiwiteit wanneer verbouingstoestande en -praktyke optimaal is. Groot variasie is egter waargeneem in die opbrengsresultate van die Regal en Prime Seedless. Dit is hoofsaaklik as gevolg van die onlangse bekendstelling van die twee cultivars in die area en dus ook die beperkte aantal blokke van die cultivars wat reeds in vol produksie was. Dit was dus onmoontlik om duidelike tendense in terme van die toekomstige produksie van volwasse Regal en Prime Seedless te identifiseer. Indikasies van arbeidsinsette en produksiekoste kon egter wel verkry word. Vroeg rypwordende Prime Seedless en Sugraone vaar baie goed in terme van die prys wat dit behaal, veral in die oesperiode voor week 50. Hierdie voordeel van hoë pryse behaal vroeg in die seisoen is egter nie altyd van toepassing op vroeë cultivars in die later rypwordende areas van die Benede-Oranjeriviergebied nie. Later in die seisoen (na week 50), wanneer die aanbod van tafeldruiwe op oorsese markte skerp toegeneem het, is Sultana Seedless gewoonlik die beste presteerder in terme van prys van die vier cultivars. Die uiteindelike prys wat deur cultivars behaal word, word tot 'n groot mate bepaal deur vraag en aanbod, kwaliteit en aanvaarding van die cultivar deur die verbruiker. Die studie en die uitkomste daarvan het 'n sterk streeks (Benede-Oranjerivier) en plaaslike (Suid-Afrika) impak, en die spesifieke resultate salongetwyfeld van waarde wees vir produseerders, uitvoerders en ander rolspelers met bestaande belange in die cultivars of vir tafeldruifproduksie as sulks. Die metodiek wat in hierdie studie gebruik is, is egter van breêr belang en wys duidelik die voordele daarvan om gedetailleerde en gekwalifiseerde inligting aangaande produksiepraktyke te hê, wat dit ook in verband bring met arbeid en gevolglike koste per aksie. Dit behoort te lei tot meer besigheidsintelligensie en realistiese beplanning deur die produseerder met betrekking tot cultivarkeuse vir 'n spesifieke produksiearea met 'n spesifieke bemarkings geleentheid. Hierdie studie het ook die weg gebaan vir soortgelyke studies, spesifiek ten opsigte van die gedetailleerde beskrywing van die metodiek wat gevestig is. Kennis van die probleme wat in hierdie studie ondervind is, kan dien as nuttige verwysing vir die beplanning en uitvoer van soortgelyke studies.

Dissertation (PhD(Agric)) -- Stellenbosch University, 2005.
ENGLISH ABSTRACT: Due to increased consumer demand for products labelled by origin, and the requirement that these labels are a guarantee of both quality and product character, there is an increasing global focus on delimitation of denominations of origin. The integrity of denominations of origin and their defensibility can be ensured through the use of terroirs as a basis for delimitation. The aims of this study were to establish the dominant environmental criteria that affect the viticultural behaviour and wine character of two important cultivars (Cabernet Sauvignon and Sauvignon blanc) in the Stellenbosch Wine of Origin District, to use an appropriate methodology to identify viticultural terroirs in this district based on these criteria and with the use of a geographic information system, and finally to use these viticultural terroirs to identify denominations of origin within the same area. A terroir can be defined as a grouping of homogenous environmental units, or natural terroir units, based on the typicality of the products obtained. Identification and characterisation of terroirs depends on knowledge of environmental parameters, the functioning of the grapevine and the characteristics of the final product. Field studies, resulting in point data, are necessary to investigate the functioning of the grapevine but in order for this information to be of use within zoning studies it must be placed in a spatial context. As a first phase in data acquisition, the Stellenbosch Wine of Origin District was characterised and natural terroir units were identified using existing digital data and a geographic information system. A natural terroir unit (NTU) can be defined as a unit of land that is characterised by relatively homogenous topography, climate, geological substrate and soil. A total of 1389 NTUs were identified in the Stellenbosch Wine of Origin District (84 537 ha). The identified NTUs were homogenous with respect to terrain morphological unit, altitude, aspect and soil type. Each of the identified units was further described with respect to the extent of the expected sea breeze effect and, for certain of the soil types, the associated parent material. As a second phase of data acquisition, a network of plots of Sauvignon blanc and Cabernet Sauvignon were delimited in commercial vineyards in proximity to weather stations and their viticultural and oenological response monitored for a period of seven years. Regression tree analyses were performed on the complete data set and the relative importance of the environmental and management related variables determined for each dependent variable. Excepting for scion clone, which had a high relative importance for bunch mass of Sauvignon blanc and yield to pruning mass index of Cabernet Sauvignon, no other non-environmental variable included in the analyses appeared to have a strong effect on grapevine performance and wine character. The performance of Cabernet Sauvignon was affected by the potassium content of the subsoil and the climate of the season. The performance of Sauvignon blanc appeared to be related to soil texture, wind exposure and temperature, both during the green berry growth stage and the month prior to ripening. From the results presented, it appears that environmental parameters have an overriding effect on the performance of both Cabernet Sauvignon and Sauvignon blanc, but that these two cultivars react differently to environmental stimuli. A knowledge-driven model used the rules generated in the regression tree analyses to directly classify natural terroir units with respect to expected response of Cabernet Sauvignon and Sauvignon blanc in the Stellenbosch Wine of Origin District. The natural terroir units were thus grouped into terroir units that were homogenous with respect to predicted viticultural and oenological response for each cultivar. The use of representative sites to determine the response of the grapevine to its environment is time consuming and costly and limits terroir studies to research related investigations. Vineyard managers were therefore surveyed with respect to the functioning of established Sauvignon blanc vineyards in the Stellenbosch Wine of Origin District in an attempt to obtain the necessary data. Comparison of the data generated with these questionnaires to measured data in commercial vineyards suggested that the vineyard managers were able to characterise the performance of vineyards with respect to vigour, signs of drought stress and yield. Each vineyard was mapped and the responses were linked to modelled environmental variables. Classification and regression trees were used to construct decision trees, which could be applied to environmental data in a geographic information system to determine viticultural terroirs for production of Sauvignon blanc. These terroirs, although fewer, were comparable to those generated using field data. Data gathered during terroir studies, and the identified viticultural terroirs for Cabernet Sauvignon and Sauvignon blanc, were used to revisit the boundaries of the Stellenbosch Wine of Origin District and the Simonsberg-Stellenbosch ward. Modifications were proposed based on expected wine characteristics. Boundaries for two new wards in the Helderberg basin were proposed. It was also possible to identify vineyards within a ward for the production of terroir specific wines.
AFRIKAANSE OPSOMMING: Toenemende verbruikersaanvraag vereis produkte waarvan die etikette nie net die oorsprong aandui nie, maar ook kan dien as ‘n waarborg vir die produk se kwaliteit en kenmerkendheid. Hierdie tendens verklaar die toenemende wereldwye fokus op afgebakende areas van oorsprong. Die integriteit van die afgebakende areas van oorsprong sowel as hul verdedigbaarheid kan gewaarborg word deur terroirs as basis vir afbakening te gebruik. Die doelstellings van die studie was om die oorheersende omgewingseienskappe wat wingerdprestasie en wynkarakter van twee belangrike cultivars, naamlik Cabernet Sauvignon en Sauvignon blanc, in die Stellenbosch Wyn van Oorsprongsdistrik bemvloed, te bepaal; tweedens om ‘n toepaslike metodologie te gebruik om terroirs in die die distrik te bepaal wat gebaseer is op die geidentifiseerde omgewingseienskappe met die gebruik van ‘n geografiese inligtingstelsel; en, ten slotte, om hierdie terroirs vir wingerbou te gebruik om afgebakende areas van oorsprong in dieselfde omgewing te identifiseer. ‘n Terroir kan gedefinieer word as ‘n samestelling van homogene omgewingseenhede, of natuurlike terroir-eenhede (NTE), wat gebaseer word op die kenmerkende eienskappe van die produkte wat daaruit verkry word. Identifisering en karakterisering van terroirs sal afhang van kennis van die omgewingsparameters, die funksionering van die wingerdstok en die eienskappe van die finale produk. Veldstudies waaruit puntdata verkry word, is noodsaaklik om die funksionering van die wingerdstok te ondersoek. Dit is egter noodsaaklik om eers hierdie inligting in ruimtelike konteks te plaas alvorens die inligting vir soneringstudies gebruik kan word. As 'n eerste fase van datagenerering, was die Stellenbosch Wyn van Oorsprongsdistrik gekarakteriseer en NTE’s geidentifiseer deur gebruik te maak van bestaande digitale data en ‘n geografiese inligtingstelsel. ‘n NTE kan gedefinieer word as ‘n landseenheid wat gekarakteriseer word deur ‘n relatiewe homogene topografie, klimaat, geologiese substraat en grondtipe. ‘n Totaal van 1389 NTE’s is geidentifiseer in die Stellenbosch Wyn van Oorsprongsdistrik (84 537 ha). Die geidentifiseerde NTE’s was homogeen met betrekking tot die terrein morfologiese eenheid, hoogte bo seespieSI, hellingsaspek en grondtipe. Elk van die geidentifiseerde eenhede was verder beskryf volgens die omvang van die seewindinvloed en, vir toepaslike grond tipes, die geassosieerde moedermateriaal. As ‘n tweede fase van datagenerering is ‘n netwerk van persele van Cabernet Sauvignon en Sauvignon blanc afgebaken binne bestaande kommersiele wingerde in die nabyheid van weerstasies. Hul wingerd- en wynkundige respons is vir ‘n periode van sewe jaar gemonitor. Regressieboomanalises is gebruik om die volledige stel data te analiseer en om die relatiewe belang van omgewings- en bestuurspraktykverbonde veranderlikes te bepaal. Die bostokkloon (wat 'n hoe relatiewe belang vir die trosmassa van Sauvignon blanc en die oes- tot snoeimassa verhouding van Cabernet Sauvignon het) is die enigste van die nie-omgewingsparameter wat ‘n sterk invloed op wingerdprestasie of wynkarakter blyk te he. Die prestasie van Cabernet Sauvignon is beTnvloed deur die kaliuminhoud van die ondergrond sowel as die seisoensklimaat. By Sauvignon blanc het dit voorgekom of die prestasie verband hou met grondtekstuur, windblootstelling en temperatuur tydens die groen fase van korrelgroei sowel as die maand voor rypwording. Alhoewel dit blyk uit die resultate dat omgewingsparameters 'n oorheersende invloed op die prestasie van beide Cabernet Sauvignon en Sauvignon blanc uitoefen, reageer die twee cultivars verskillend op omgewingsprikkels. ‘n Kennisgedrewe model waarvan die riglyne uit resultate van die regressieboomanalise saamgestel is, word gebruik om NTE direk te klassifiseer ten opsigte van die verwagte respons van Cabernet Sauvignon en Sauvignon blanc in die Stellenbosch Wyn van Oorsprongsdistrik. Die NTE is dus gegroepeer om terroir eenhede te vorm wat homogeen was ten opsigte van die verwagte wingerd- en wynkundige respons vir elke cultivar. Die gebruik van verwysingspersele om die respons van die wingerdstok teenoor sy onmiddelike omgewing te bepaal, is tydrowend en duur en beperk sodoende terroir studies tot navorsing. Gevolglik is ‘n opname onder wingerdbestuurders gemaak om inligting oor die prestasie van Sauvignon blanc in die Stellenbosch Wyn van Oorsprongsdistrik in te win en sodoende die nodige data te verkry. Na vergelyking van die ingewinde data, wat uit die opname verkry is, met gemete data vanaf kommersiele wingerde, kon afgelei word dat wingerdbestuurders by magte is om die prestasie van wingerde ten opsigte van groeikrag, tekens van droogtestres en opbrengs te karakteriseer. Elke wingerd is gekarteer en die respons is gekoppel aan die gemodeleerde omgewingsparamters. Klassifikasie en regressiebome is gebruik om besluitnemingsmodelle saam te stel wat toegepas kon word op omgewingsdata in ‘n geografiese inligtingstelsel om terroirs vir die produksie van Sauvignon blanc te bepaal. Hierdie terroirs, alhoewel minder, was vergelykbaar met die wat gegenereer was met behulp van veldstudies. Data verkry met terroirstudies, sowel as gei'dentifiseerde terroir-eenhede, was gebruik om die grense van die Stellenbosch Wyn van Oorsrongsdistrik en die Simonsberg-Stellenbosch wyk te herbepaal. Voorgestelde modifiserings was gebaseer op verwagte wyneienskappe. Grense vir twee nuwe wyke in die Helderbergkom is voorgestel. Dit was ook moontlik om wingerde binne ‘n wyk te identifiseer vir die produksie van terroir-spesifieke wyne.

Thesis (MScAgric)--University of Stellenbosch, 2005.
ENGLISH ABSTRACT: Wind, as a component of the environment, contributes to the viticultural concept of terroir in the South Western Cape region of South Africa. Many other components also contribute to terroir (e.g. soil, altitude, direction of slope, etc.) and it is difficult to quantify the contribution of each. A good terroir promotes slow and complete ripening of the berries. A vineyard on such a terroir produces good quality crops over time and the effects of climatic extremes on the performance of the vine are limited by this terroir. Although grapevines in the South Western Cape are exposed to strong synoptic southerly and southeasterly winds during the growing season and sea breezes add to the effect of wind in coastal areas, little is known about the effect of wind on grapevine performance. This preliminary study was undertaken to obtain more information on the effect of wind on some morphological and reproductive characteristics of Merlot nair. The aim was to obtain preliminary data which can serve as a basis for future studies on the effect of wind on grapevine performance. Important differences .in wind speed were measured spatially in a selected vineyard and exposure to wind was observed to result in essential viticultural differences. The effect of wind on vegetative parameters, canopy density, yield, berry composition and wine quality was investigated. Wind caused leaves on primary shoots of exposed vines to be smaller, but increased lateral growth in their fruiting zones. Sheltered vines had longer shoots but no significant differences were measured concerning cane diameter and pruning mass. Although it was expected that sheltered vines would have denser canopies, similar canopy densities were measured for both treatments. Vines exposed to wind responded with decreased stomatal conductance. As a result, leaf temperature was affected, showing differences between sheltered and exposed vines. Sheltered vines had more bunches per vine but fewer berries per bunch. As a result, bunches of sheltered vines were smaller than those of exposed vines. No significant difference was observed concerning the yield under the two treatments. The effect of wind on stomatal conductance had an essential impact on berry composition, thus directly influencing the quality of wine. Grapes from exposed vines showed a higher colour index. Berries from sheltered vines had significantly lower pH values and potassium concentrations and the malic acid content was lower than in berries from exposed vines. Wine from sheltered vines had more vegetative undertones in comparison with the stronger fruity character of exposed vines. A better acid balance, together with superior complexity (fullness/mouth feel), contributed to the better overall quality identified during the evaluation of wine produced from sheltered vines.
AFRIKAANSE OPSOMMING: Wind as 'n omgewingsfaktor dra by tot die wingerdkundige konsep van terrair in die Suidwes-Kaap streek van Suid-Afrika. Baie ander komponente dra ook by tot terrair (bv. grond, hoogte bo seespieël, rigting van helling, ens.) en dit is moeilik om die bydrae van elk te kwantifiseer. 'n Goeie terrair bevorder stadige en volledige rypwording van die korrels. 'n Wingerd gevestig op so 'n terrair produseer jaarliks hoë kwaliteit oeste met goeie sapsamestellings en die terrair beperk die negatiewe invloed van uiterste klimaatsomstandighede op wingerdprestasie. Alhoewel wingerde in die Suidwes-Kaap gedurende die groeiseisoen aan sterk sinopties suidelike en suid-oostelike winde blootgestel is en seebriese 'n bykomstige effek in kusgebiede het, is daar beperkte kennis oor die effek wat wind op wingerdprestasie het. Hierdie voorlopige studie is onderneem om meer inligting oor die effek van wind op sommige morfologiese en reproduktiewe eienskappe van Merlot noir in te win. Die mikpunt was om verwysingsdata in te samel wat as 'n basis vir toekomstige studies oor die effek van wind op wingerdprestasie kan dien. Belangrike verskille in windspoed is gemeet in die geselekteerde wingerd en waarnemings het getoon dat blootstelling aan wind tot kenmerkende wingerdkundige verskille gelei het. Die effek van wind op vegetatiewe parameters, lowerdigtheid, oesgrootte, druifsamestelling en wynkwaliteit is ondersoek. Wind het kleiner blare op primêre lote van wind-blootgestelde stokke veroorsaak, maar het laterale groei in hul trossones verhoog. Wind-beskermde stokke het langer lote gehad maar geen noemenswaardige verskille is ten opsigte van lootdeursnee en snoeimassa gemeet nie. Die verwagting was dat beskermde stokke digter lower sal hê, maar soortgelyke lowerdigthede is vir beide beskermde en wind-blootgestelde stokke gemeet. Stokke blootgestel aan wind het met 'n verlaagde huidmondjiegeleiding gereageer. Gevolglik is blaartemperatuur beïnvloed, met verskille tussen beskermde en blootgestelde wingerde. Beskermde stokke het meer trosse per stok maar minder korrels per tros gehad. As gevolg hiervan was die trosse van beskermde stokke kleiner as die van blootgestelde wingerde. Geen noemenswaardige verskille in die oesgroottes is tussen die twee behandelings gemeet nie. Die effek van wind op huidmondjiegeleiding het 'n belangrike impak op druifsamestelling gehad en het daarom 'n direkte invloed op wynkwaliteit gehad. Druiwe van blootgestelde stokke het 'n hoër kleurindeks getoon. Die pH en kaliumkonsentrasie van druiwe van beskermde stokke was merkbaar laer en het minder appelsuur gehad as die van die blootgestelde stokke. Die wyn van beskermde stokke het meer vegetatiewe geure gehad in vergelyking met die sterker vrugtige karakter van blootgestelde stokke. 'n Beter suurbalans, tesame met goeie kompleksiteit (volheid/mondgevoel), het egter meegebring dat beskermde stokke 'n beter wyngehalte lewer.

Thesis (MScAgric)--University of Stellenbosch, 2004.
ENGLISH ABSTRACT: Due to the extraordinary drought resistance of the grapevine, viticulture without irrigation in the winter rainfall coastal areas of South Africa is a feasible and commonly used practice. Wine quality is largely determined by the quality of the grapes from which it is made. Grapevine physiology is affected both directly and indirectly by water stress, which may vary according to soil type and prevailing atmospheric conditions. The water status of the grapevine can affect grape composition profoundly, either directly or indirectly, in either a positive or negative way, depending on the degree as well as the duration of water stress. There are three important factors involved in the development of water stress, namely the transpiration rate, the rate of water movement from the soil to the roots, and the relationship of soil water potential to leaf water potential. All three these factors are affected by atmospheric and/or soil conditions. In warm winelands such as South Africa (Western Cape), with a mediterranean climate which is characterised by a hot, dry summer period, the most important characteristic of soil is its ability to supply sufficient water to the grapevine during the entire growing season. Leaf water potential (Ψl) has gained wide acceptance as a fundamental measure of grapevine water status, and has been widely applied in viticultural research. Shortly before dawn, Ψl approaches equilibrium with soil water potential and reaches a maximum daily value. The study formed an integral part of a comprehensive, multi-disciplinary research project (ARC Infruitec-Nietvoorbij Project No. WW13/01) on the effect of soil and climate on wine quality, which commenced in 1993 and will be completed in 2004. This study was conducted during the 2002/03 growing season in two Sauvignon blanc vineyards situated at Helshoogte and Papegaaiberg, both in the Stellenbosch district, approximately nine kilometres apart. Two experiment plots, representing contrasting soil types in terms of soil water regime, were selected in each vineyard. At Helshoogte the two soils represented the Tukulu and Hutton forms, and the soils at Papegaaiberg were of the Avalon and Tukulu forms. The aim of this study was to determine the effect of atmospheric conditions and soil water status on the level of water stress in the grapevines for each soil at each locality, as well as the effect of grapevine water stress on yield and wine quality. This was done by determining and comparing the soil water status, soil water holding capacity of the soils and the evapotranspiration of the grapevines on the two different soils, at each of the two localities differing in mesoclimate and topography. The atmospheric conditions at the two localities during the 2002/03 season were also determined and compared to the long-term average atmospheric conditions, and the level of water stress of grapevines on each soil at each locality was measured. During the 2002/03 growing season, atmospheric conditions were relatively warm and dry in comparison to the long-term averages of previous seasons. These conditions accentuated the effects of certain soil properties that may not come forward during wetter, normal seasons. The usually wet Tukulu soil at Helshoogte was drier than expected during the 2002/03 season compared to the Hutton soil. Due to more vigorous growth on the Tukulu soil, grapevines extracted more soil water early in the season, leading to a low soil water matric potential and more water stress in the grapevines. Due to the higher vigour, resulting in more canopy shading, and more water stress, the dominant aroma in wines from the Tukulu soil was fresh vegetative. The Hutton soil maintained consistency with regards to both yield and wine quality compared to previous seasons. On the other hand the Tukulu soil supported a higher yield, but with lower than normal wine quality. The Avalon soil at Papegaaiberg maintained the highest soil water potential towards the end of the season, probably due to capillary supplementation from the sub-soil. Grapevines on the Tukulu soil at Papegaaiberg experienced much higher water stress than ones on the other three soils, especially during the later part of the season. This could be ascribed to a combination of factors, the most important being the severe soil compaction at a shallow depth, seriously limiting rooting depth and root distribution, which is detrimental to grapevine performance. Both the soil water status and atmospheric conditions played important roles in determining the amount of water stress that the grapevines experienced at different stages. The air temperature and vapour pressure deficit throughout the season were consistently lower at Helshoogte, the cooler terroir, compared to Papegaaiberg, the warmer terroir. At flowering, Ψl was lower for grapevines at Helshoogte than at Papegaaiberg, showing that diurnal grapevine water status was primarily controlled by soil water content. The difference in grapevine water status between the two terroirs gradually diminished until it was reversed during the post harvest period when Ψl in grapevines at Papegaaiberg tended to be lower compared to those at Helshoogte. The relatively low pre-dawn Ψl at Helshoogte indicated that the grapevines were subjected to excessive water stress resulting from the low soil water content. However, grapevines at Helshoogte did not suffer material water stress (i.e. Ψl < -1.20 MPa) during the warmest part of the day, suggesting that partial stomatal closure prevented the development of excessive water stress in the grapevines. This suggests that low pre-dawn Ψl values do not necessarily imply that grapevines will experience more water stress over the warmer part of the day, or visa versa. This does not rule out the possibility that side-effects of partial stomatal closure, such as reduced photosynthesis, can have negative effects on grapevine functioning in general. These results also suggest that measurement of diurnal Ψl cycles at various phenological stages is required to understand and quantify terroir effects on grapevine water status.
AFRIKAANSE OPSOMMING: Danksy die droogteweerstand van die wingerdstok is die verbouing van wingerde sonder besproeiing ‘n praktiese en algemene verskynsel in die winterreënval-areas van Suid-Afrika. Wynkwaliteit word grootliks bepaal deur die kwaliteit van die druiwe waarvan dit gemaak word. Wingerdfisiologie word direk en indirek beïnvloed deur waterstres, wat kan varieer volgens die grondtipe en die heersende atmosferiese toestande. Die waterstatus van die wingerdstok beïnvloed druifsamestelling, direk of indirek, en positief of negatief, afhangend van die graad en tydsduur van die waterstres. Daar is drie belangrike faktore betrokke by die ontwikkeling van waterstres, naamlik die transpirasietempo, die tempo van waterbeweging vanaf die grond na die wortels, en die verhouding tussen die grondwatermatrikspotensiaal tot blaarwaterpotensiaal. Al drie die faktore word beïnvloed deur die atmosferiese en/of grondtoestande. In warm wynboulande soos Suid-Afrika (Weskaap), met ‘n meditereense klimaat wat gekarakteriseer word deur ‘n warm, droë somerperiode, is die belangrikste eienskap van grond die vermoë om voldoende water aan die wingerdstok te verskaf gedurende die hele seisoen. Blaarwaterpotensiaal (Ψl) het wye aanvaarding bekom as die fundamentele meting van wingerstokwaterstatus, en word wyd toegepas in wingerdkundige navorsing. Kort voor sonsopkoms, nader Ψl ‘n ewewig met die grondwatermatrikspotensiaal en bereik ‘n maksimum daaglikse waarde. Die studie vorm ‘n integrale deel van ‘n omvattende, multi-dissiplinêre navorsingsprojek (ARC Infruitec-Nietvoorbij Projek No. WW13/01) op die effek van grond en klimaat op wynkwaliteit, wat in 1993 in aanvang geneem het en in 2004 afgehandel sal word. Hierdie studie is uitgevoer gedurende die 2002/03 seisoen in twee Sauvignon blanc wingerde geleë by Helshoogte en Papegaaiberg, beide in die Stellenbosch distrik, ongeveer nege kilometer van mekaar. Twee eksperimentele persele, elkeen verteenwoordigend van kontrasterende grondtipes in terme van grondwaterregime, is geselekteer in elke wingerd. By Helshoogte word die twee gronde verteenwoordig deur die Tukulu en Hutton grondvorms, en die gronde by Papegaaiberg is van die Avalon en Tukulu vorms. Die doel van die studie was om die effek van atmosferiese toestande en grondwaterstatus op die wingerdstok se waterstatus vir elke grond by die twee lokaliteite te bepaal, sowel as die effek van die wingerdstok se waterstatus op die opbrengs en wynkwaliteit. Dit is gedoen deur die grondwaterstatus, die grondwaterhouvermoë, sowel as die evapotranspirasie van die wingerdstokke op die twee verskillende gronde by elk van die twee lokaliteite, wat verskil in mesoklimaat en topografie, te bepaal en vergelyk. Die atmosferiese toestande by die twee lokaliteite gedurende die 2002/03 seisoen is ook bepaal en vergelyk met die langtermyn gemiddelde atmosferiese toestande. Die vlakke van waterstres in wingerdstokke op elke grond by elke lokaliteit is ook gemeet. Gedurende die 2002/03 groeiseisoen, was die atmosferiese toestande relatief warm en droog in vergelyking met die langtermyn gemiddeldes van vorige seisoene. Hierdie kondisies aksentueer die effek van sekere grondeienskappe wat nie noodwendig na vore kom gedurende normale, natter seisoene nie. Die gewoonlike nat Tukulu grond by Helshoogte was droër as verwag gedurende 2002/03 in vergelyking met die Hutton grond. As gevolg van sterker groekrag op die Tukulu grond, het wingerdstokke meer grondwater onttrek vroeg in die seisoen, wat gelei het tot ‘n lae grondwatermatrikspotensiaal en meer waterstres in die wingerdstokke. Die sterker groeikrag het meer beskaduwing van die lower asook meer waterstres veroorsaak, wat gelei het daartoe dat die dominante aroma in wyne vanaf druiwe op die Tukulu grond vars vegetatief was. Die Hutton grond het bestendig gebly in terme van opbrengs en wynkwaliteit in vergelyking met vorige seisoene. Daarteenoor het die Tukulu grond ‘n hoër opbrengs gelewer, maar met laer as gewoonlike wynkwaliteit. Die Avalon grond by Papegaaiberg het die hoogste grondwatermatrikspotensiaal behou tot die einde van die seisoen, heelwaarskynlik a.g.v. kapillêre aanvulling vanuit die ondergrond. Wingerdstokke op die Tukulu grond by Papegaaiberg het heelwat meer waterstres ondervind as op die ander drie gronde, veral later in die seisoen. Dit kan toegeskryf word aan ‘n kombinasie van faktore, die belangrikse daarvan die erge grondkompaksie vlak in die grond, wat worteldiepte en -verspreiding ernstig beperk het, wat op sy beurt nadelig is vir wingerdprestasie. Beide die grondwaterstatus en atmosferiese toestande het ‘n belangrike rol gespeel in die bepaling van die hoeveelheid waterstres wat die wingerdstok op verskillende stadiums ondervind het. Die lugtemperatuur en waterdampdruktekort was regdeur die seisoen laer by Helshoogte, die koeler terroir, as by Papegaaiberg, die warmer terroir. Gedurende blom was die Ψl laer vir wingerdstokke by Helshoogte as by Papegaaiberg, wat daarop wys dat daaglikse wingerdstok waterstatus hoofsaaklik deur die grondwaterinhoud bepaal was. Die verskil in wingerdstok waterstatus tussen die twee terroirs het geleidelik verminder totdat dit omgekeer was gedurende die na-oes periode toe Ψl in wingerdstokke by Papegaaiberg geneig het om laer te wees in vergelyking met die by Helshoogte. Die relatiewe lae voorsonop Ψl by Helshoogte het daarop gedui dat die wingerdstokke aan oormatige waterstres onderwerp was. Die wingerdstokke by Helshoogte het egter nie materiële waterstres (i.e. Ψl < -1.20 MPa) gedurende die warmste gedeelte van die dag ondervind nie, wat aandui dat gedeeltelike huidmondjiesluiting plaasgevind het om die ontwikkeling van oormatige waterstres te verhoed.Dit dui aan dat lae voorsonop Ψl waardes nie noodwendig impliseer dat wingerdstokke meer waterstres gedurende die warmste gedeelte van die dag sal ondervind nie, of visa versa. Dit sluit nie die moontlikheid uit dat negatiewe neweeffekte van gedeeltelike huidmondjiesluiting, soos ‘n vermindering in fotosintese, ‘n negatiewe effek kan hê op die wingerdstok se funksionering in die algemeen nie. Hierdie resultate stel voor dat die meting van daaglikse Ψl siklusse gedurende verskeie fenologiese stadia benodig word om die effek van terroir op die wingerdstok se waterstatus te verstaan en te kwantifiseer.

Thesis (MScAgric (Agricultural Economics))--University of Stellenbosch, 2009.
AFRIKAANSE OPSOMMING: Die Wes-Kaapprovinsie van Suid-Afrika beskik oor ’n diverse kapasiteit wat landbouproduksie betref en dit dra tot die sektor se algemene stabiliteit by; vandaar die bevordering van die Wes-Kaap as ’n aantreklike beleggingsektor. Die wynbedryf, wat ’n belangrike integrerende deel van die landbousektor in die Wes-Kaap uitmaak, speel ’n baie belangrike rol in die ekonomie van die Provinsie en bied ontsaglike geleenthede met betrekking tot landboukundige beleggings in die Provinsie. Die Suid-Afrikaanse wynbedryf is bekend vir sy produkte van hoë gehalte. Tans word indirekte aanwysers soos die inkomste van produsente, die aantal nuwe wynkelders, asook die ouderdomsamestelling van wingerdstokke in Suid-Afrika, gebruik om die beleggings- netto toevloeiing in die wynbedryf te bereken. Die hoofdoel van hierdie studie is om die mees algemene bronne van kapitaal van wynplase en die mees algemene doelwitte wat wynboere in die Wes-Kaap probeer om te bereik, te identifiseer. Nog ’n doelwit is om daardie wynplaas- en eienaarskenmerke te identifiseer wat die prestasie van wynplase in die Wes-Kaapprovinsie van Suid-Afrika beïnvloed. Om die ontleding te vergemaklik is die hoofprobleem in drie spesifieke doelwitte of subprobleme verdeel. Die studie het van verskeie metodes en tegnieke gebruik gemaak in ’n poging om relevante en akkurate data te verkry. Die verskillende bronne wat geraadpleeg is het persoonlike beraadslaging met deskundiges in die bedryf, artikels wat in verskeie akademiese vaktydskrifte en boeke gepubliseer is, referate wat by konferensies gelewer is, verhandelings van nagraadse studente, en ander artikels op die Internet ingesluit. Data-ontledings wat met die eerste en tweede subprobleme verband gehou het is met die gebruik van statistiese pakkette soos Excel en Stata in die vorm van veelvoudige kruistabulerings uitgevoer. In die derde probleem, naamlik om wynplaas- en eienaarskenmerke te identifiseer wat die prestasie van wynplase in die Wes-Kaap beïnvloed, is ’n intervalregressiegelykstelling bereken deur van die Stata- statistiese sagtewarepakket gebruik te maak.
ENGLISH ABSTRACT: The Western Cape Province of South Africa has a diverse agricultural production capacity and this contributes to the sector’s general stability, hence its promotion as an attractive investment sector. The wine industry, a significant component of the agricultural sector in the Western Cape, plays a very important role in the economy of the Province and presents enormous opportunities in terms of agricultural investments in the Province. The South Africa’s wine industry is renowned for its high quality products. Currently, indirect indicators such as producer income, the number of new wine cellars, as well as the age composition of vines in South Africa, are used to estimate investment net flows into the wine industry. The main objectives of this study are to identify the most common sources of capital in wine farms and the most common objectives that wine farm owners are trying to achieve in the Western Cape Province. Another objective is to identify those wine farm and owner characteristics that affect the performance of wine farms in the Western Cape Province of South Africa. For ease of analysis, the main problem was divided into three specific objectives or sub-problems. The study employed a number of methods and techniques in an effort to obtain relevant and accurate data. The different sources consulted include personal communications with industry experts, articles published in different academic journals and books, conference papers, postgraduate students’ theses, and other articles from the internet. Data analyses relating to the first and second sub-problems were carried out using Excel and Stata statistical packages and took the form of multiple cross-tabulations. In the third subproblem i.e., to identify wine farm and owner characteristics that affect the performance of wine farms in the Western Cape, an interval regression equation was estimated using Stata statistical software package.

Thesis (MA (Geography and Environmental Studies))--University of Stellenbosch, 2009.
The acceleration of biodiversity loss is understood to threaten the ecosystems upon which life on earth depends. Existing conservation approaches have proved insufficient to stem global biodiversity losses. Mounting evidence indicates that responsible biodiversity conservation requires an integration of ecology with economics. Accordingly, contemporary conservation interventions incorporate a concept that ecosystems and biodiversity can be used and also conserved. In South Africa, such interventions can be appropriately applied in the Cape Floristic Region (CFR), an area containing severely endangered biodiversity where land use and conservation goals rarely mesh. More than 80% of land in the CFR is privately owned, with large tracts transformed for viticulture. Conservation challenges thus include the reconciliation of wine production needs with biodiversity protection necessities. This thesis comprises a case study of the Biodiversity and Wine Initiative, an organisation that simultaneously promotes biodiversity conservation in the South African wine sector, by a process of mainstreaming within an viticultural context. The overall study aim was to improve understanding of the BWI as a mainstreaming initiative. Specifically, the area of inquiry is an investigation into how effectively the BWI has protected biodiversity in the CFR between 2005 and 2008. Individual aims were to investigate reductions in threat to biodiversity in the CFR; to assess farmer adoption levels of BWI strategy; and to formulate a sustainability appraisal of the Biodiversity and Wine Initiative. A strategic triangulation of methods was employed. Stakeholder interviews were conducted to probe adoption levels and opinions of BWI strategy. Case studies of two BWI champion estates provided data on best practice. Towards a critical appraisal of sustainability, an assessment was made of the BWI as a functioning mainstreaming model, which included case studies of two model farms.

Thesis (MScAgric (Soil Science))--University of Stellenbosch, 2011.
Includes bibliography.
ENGLISH ABSTRACT: The natural resource condition or health has been accepted as a valuable indicator of sustainable land use. The assessment of soil health (quality) has become a valuable tool in determining the sustainability of land management systems. This work aims to evaluate the sustainability of soil management practices in agricultural extension for vineyards in Robertson, South Africa based, on the current approach of the concept of soil health and soil quality, as well as to briefly explore the present reservations regarding the definition of the concept. The soil management treatments include a mechanical weed control, chemical weed control, annual addition of straw mulch, annual cover crop and perennial cover crop. The objective of study is to (i) identify suitable soil health (quality) indicators for vineyards in the study area; (ii) analyze the soil health (quality) indicators for different soil management treatments; (iii) evaluate the effect of various soil management treatments on the overall soil functionality, by comparing measured indicators to the soil property threshold values, for optimal vine growth; iv) establish a more consistent understanding and use of the terms health and quality, as understood and used in the general science community, with particular reference to the public health system. The soil physical, chemical and biological properties which were selected as indicators of soil health (quality) based on specific criteria similar to previous work done on the concept. The properties selected include soil texture, gravimetric water content, bulk density, soil aeration, water aggregate stability, soil pH, EC, available N,P,K , soil organic matter content, soil microbial biomass, potential mineralizable nitrogen and soil respiration. The study makes use of methods of analysis previously used for soil health and soil quality assessments, as well as soil analytical methods as accepted by experienced soil scientist within the study area. The soil was sampled on three separate events to depths of 0-200 mm for initial characterization of soil and 0-50 mm to compare soil health (quality) Between tracks and In tracks of treatment plots. The values obtained for each property were compared with the optimum for vineyards and ranked accordingly. The treatment that resulted in the most desirable soil health (quality) was the straw mulch and perennial cover crop treatments.
AFRIKAANSE OPSOMMING: Die toestand of gesondheid van natuurlike hulpbronne is aanvaar as `n waardevolle aanduiding van volhoubare grondgebruik. Die assessering van grond gesondheid (kwaliteit) is 'n waardevolle hulpmiddel in die bepaling van die volhoubaarheid van grond bestuur stelsels. Hierdie werkstuk poog om die volhoubaarheid van grond bestuurs praktyke te evalueer vir wingerde in Robertson, Suid-Afrika wat baseer is op die huidige benadering van grond gesondheid en kwaliteit. Die tesis dek ook die huidige onsekerhede oor die konsep en definisies van terme wat gebruik word in die konsep. Die grond bestuur praktyke sluit in 'n meganiese onkruidbeheer, chemiese onkruidbeheer, jaarlikse toevoeging van `n strooi deklaag, jaarlikse en meerjarige dekgewas dekgewasse. Die doel van die studie was om (i) die geskikte grond gesondheid (kwaliteit) indikators vir wingerde in die studie area te identifiseer, (ii) die grond gesondheid (kwaliteit) indikators vir verskillende bogrond bestuur praktyke te identifiseer; (iii) die effek van verskillende grond bestuur praktyke op die algehele grond funksies te evalueer, deur dit te vergelyk met die gemete indikators vir drempelwaardes vir optimale wingerd groei; iv) 'n meer konsekwente begrip en gebruik van die terme “gesondheid” en “kwaliteit” vas te stel, soos dit verstaan en gebruik word in die algemene wetenskaplike gemeenskap, met spesifieke verwysing na die openbare gesondheidsisteem. Die grond fisiese, chemiese en biologiese eienskappe wat as indikators van grond gesondheid (kwaliteit) geselekteer was, word gebaseer op spesifieke kriteria soortgelyk aan dié wat in vorige werk op die konsep gedoen was. Die eienskappe wat geselekteer is sluit in grondtekstuur, gravimetriese waterinhoud, bulk digtheid, grond deurlugting, totalle water stabiliteit, grond pH, electriese geleiding, toeganklike N, P, K, grond organiese materiaal inhoud, grond mikrobiese massa, potensiële mineraliseerbare stikstof en grond respirasie. Die studie maak gebruik van analitiese metodes wat voorheen gebruik was vir grond gesondheid en kwaliteit, sowel as die grond analitiese metodes soos gebruik deur ervare grondkundiges binne die studie gebied. Die grondmonsters was geneem op drie afsonderlike geleenthede oor dieptes van 0-200 mm vir die aanvanklike karakterisering van grond en 0-50 mm, om grond gesondheid (kwaliteit) Tussen trekkerspore en In trekkerspore van die persele te vergelyk. Die waardes verkry vir elke eienskap was vergelyk met die optimum vir wingerde en verdeel volgens kwaliteit. Die behandeling wat die mees optimale grond gesondheid (kwaliteit) getoon het, was die strooi deklaag en meerjarige dekgewas behandelings.

Thesis (MScAgric)--Stellenbosch University, 1999.
ENGLISH ABSTRACT: The purpose of the study is to determine the rate of return to cover crop research in the wine industry. The method followed will prove an invaluable contribution toward the need to determine a suitable approach for evaluation studies. The importance behind such a study is the development of appropriate ex ante evaluation approaches, which will assist in the allocation of public research resources in both a social and economical manner. The wine industry is currently enjoying healthy international demand, but will need to remain competitive to reap the full benefit of international exposure. The need therefore exists for a continuation of research at the institutional level, in order to maintain the progressive nature of research knowledge that was available in the past. The evaluation of ex post and ex ante research will assist in maintaining government funding for research and help with campaigning for private investment of research in the wine industry. The use of two evaluation approaches was used for the analysis. Firstly, the production function approach achieved a rate of return of 44 percent, using weather and research expenditure as a means to explain the variations in wine grape yield. Secondly, a cost benefit approach was devised in order to make a direct comparison between the cost and benefits related to the cover crop research. The rate of return achieved for this mode of analysis is 37 percent, using trial plot data as a source of information on potential benefits. In addition to this the cost benefit approach was used to show the difference in rate of return that is achievable between two growing regions. The variable that exists between the two regions, is the higher rate of irrigation in one of the regions. The high rate of return achieved for the investment, provides suitable motivation for the increase in state funding for research in the wine industry, and provides valuable information for the enticement of support by private investors. The two methods used in the study will both draw a certain amount of criticism, largely as a result of the lack of available data. The empirical nature of the approaches is however simple and applicable down to the project level.
AFRIKAANSE OPSOMMING: Die doel van hierdie studie is om die opbrengs op navorsing oor dekgewasse in die Suid- Afrikaanse wynbedryf te bepaal. Hierbenewens het die studie dit ook ten doel om gepaste metodieke vir die evaluering van navorsingsprojekte daar te stel. In hierdie opsig maak hierdie studie ' n bydrae tot besluitneming oor die allokering van openbare fondse vir landbounavorsing op 'n ekonomies en sosiale optimale wyse. Die Suid- Afrikaanse wynbedryf beleef tans ' n bloeifase, hoofsaaklik as gevolg van sterk internasionale vraag na sy produkte, maar salop sy internasionale mededingendheid moet let indien die volle voordele hiervan benut kan word. Daarom is dit noodsaaklik dat die bedryf op tegnologiese gebied moet kan meeding, en dus dat navorsingsbesteding nie onoordeelkundig ingekort word rue. Inligting oor die opbrengs op navorsingsbesteding is dus noodsaaklik om die volgehoue betrokkenheid van die staat te kan regverdig, hetsy as finansier of as katalisator vir privaatsektor betrokkenheid. In hierdie studie is die opbrengs op navorsing gemeet deur beide die bekende produksiefunksie benadering sowel as deur koste-voordeel ontleding. In die eerste geval is 'n opbrengskoers van 44% gemeet, en in die tweede geval is dit 37%. By die kostevoordeel ontleding is ook 'n verdere onderskeid gemaak tussen twee wynbou-streke om die invloed van meer besproeiing te bepaal. Ten spyte van dataprobleme, veral wat betref die koste van navorsing, kan beweer word dat die inligting so verkry van nut sal wees vir besluitnemers by die toekenning van skaars navorsingsfondse, asook by bedinging om privaatsektor fondse.

Thesis (MScAgric)--Stellenbosch University, 2011.
ENGLISH ABSTRACT: Shiraz/110R grapevines, growing in a fine sandy loam soil in the Breede River Valley, were subjected to ten different drip irrigation strategies during the 2006/07, 2007/08 and 2008/09 seasons. Grapevines of the control treatment (T1) were irrigated at 30% to 40% plant available water (PAW) depletion throughout the growing season. Grapevines of three treatments were irrigated at 70% to 80% PAW depletion from bud break until véraison (i.e. when ca. 95% of grape berries have changed colour), followed by either irrigation at 30% to 40% PAW depletion (T2) or a continuous deficit irrigation (CDI) strategy (T3) or irrigation at 70% to 80% PAW depletion (T4) during ripening. The CDI strategy was obtained by applying ca. half the volume of water that was applied to the control. This allowed the soil to dry out gradually between physiological stages (i.e. bud break and véraison or véraison and harvest). Grapevines of three further treatments were irrigated at ca. 90% PAW depletion from bud break until véraison, followed by irrigation at 30% to 40% PAW depletion (T5) or a CDI strategy (T6) or irrigation at ca. 90% PAW depletion (T7) during ripening. Grapevines of two treatments were irrigated by means of a CDI strategy from bud break until véraison. For both treatments, the soil water content (SWC) was allowed to dry out gradually until ca. 90% PAW depletion was reached. After véraison, the SWC of the one treatment was maintained at ca. 90% PAW depletion by applying only four small irrigations of three hours each during ripening (T8). The soil of the other treatment, received an irrigation at véraison to refill the SWC to field capacity (T9) followed by the CDI strategy during ripening. Grapevines of the tenth treatment were irrigated at ca. 90% PAW depletion between bud break and véraison followed by a partial profile refill (PPR) strategy during ripening (T10). In order to obtain the PPR strategy, SWC was only maintained between 40% and 60% PAW depletion. Evapotranspiration varied between 3.5 mm/day and 0.1 mm/day for driest and wettest treatments, respectively, during the period between December and February. This was substantially less than the volumes required for full surface irrigation. For irrigations applied at 30% to 40% PAW depletion (T1), 70% to 80% PAW depletion (T4) and ca. 90% PAW depletion (T7) levels throughout the season, crop coefficients for the Penman-Monteith reference evapotranspiration (ETo) were 0.4, 0.2 and 0.1, respectively. Under the given conditions, the different irrigation strategies did not have any effect on root distribution and density. Shoot growth of grapevines exposed to high to severe water deficits in the pre-véraison period stopped before mid December. Shoots of grapevines that were exposed to high or severe water deficits before véraison followed by more frequent irrigation during ripening showed active re-growth. These trends occurred during all the seasons. The level of PAW depletion reflected strongly in the plant water potential in the grapevines. Leaf water potential was influenced by the prevailing atmospheric conditions, whereas stem water potential was less sensitive to atmospheric conditions, but responded more directly to soil water availability. Due to the good relationships between pre-dawn leaf, mid-day leaf, mid-day stem and total diurnal water potential, it was possible to re-classify the water status in terms of previous classifications for these water potentials based on pre-dawn measurements. Water constraints in T1, T2 and T5 grapevines were classed as experiencing no stress, whereas the T7 and T8 ones experienced strong to severe water constraints before harvest. High frequency irrigation strategies during ripening delayed sugar accumulation due to dilution of sugar in the larger berries. Except for the wettest strategy, and where grapevines were subjected to the CDI strategy throughout the season, berry mass increased during ripening, i.e. from véraison to harvest. Water deficits had a negative effect on berry mass, bunch size and yield. Where higher soil water depletion levels were allowed, irrigation strategies had a positive effect on the irrigation water productivity of grapevines compared to the frequently irrigated or CDI strategies. Higher water constraints in grapevines, particularly during ripening, improved sensorial wine colour and enhanced some of the more prominent wine aromas, e.g. spicy and berry. Grapevines that were irrigated at a high frequency during ripening produced wines with diluted character flavours and aromas and inferior overall quality. Under the given conditions, sensorial wine colour and spicy character were the dominant factors in determining overall sensorial wine quality.
AFRIKAANSE OPSOMMING: Shiraz/110R wingerdstokke in ‘n fyn sandleem grond in die Breede Rivier vallei is gedurende die 2006/07, 2007/08 en 2008/09 seisoene met tien verskillende drupbesproeiingstrategieë besproei. Wingerdstokke van die kontrole (B1) is deur die seisoen by 30% to 40% plant beskikbare water (PBW) onttrekking besproei. Drie behandelings is tussen bot en deurslaan (wanneer ca. 95% van die korrels verkleur het) by 70% tot 80% PBW onttrekking besproei, gevolg deur besproeiing by 30% tot 40% PBW onttrekking (B2), ‘n deurlopende tekort besproeiing (DTB) strategie (B3) of besproeiing by 70% tot 80% PBW onttrekking (B4) gedurende rypwording. In die geval van die DTB strategie is ongeveer die helfte van die volume water toegedien wat by die kontrole toegedien is. Laasgenoemde strategie het die grond toegelaat om geleidelik tussen fisiologiese fases (i.e. tussen bot en deurslaan of tussen deurslaan en oes) uit te droog. Drie ander behandelings is by ca. 90% PBW onttrekking tussen bot en deurslaan besproei, gevolg deur besproeiing by 30% tot 40% PBW onttrekking (B5) of ‘n DTB strategie (B6) of besproeiing by ca. 90% PBW onttrekking (B7) gedurende rypwording. Wingerdstokke van twee ander behandelings is d.m.v. ‘n DTB strategie vanaf bot tot deurslaan besproei. Beide behandelings se grondwaterinhoud (GWI) was toegelaat om geleidelik uit te droog tot ca. 90% PBW onttrekking bereik was. Na deurslaan was die GWI van die een behandeling naby ca. 90% PBW onttrekking gehandhaaf deur slegs vier klein besproeiings van drie uur elk gedurende rypwording toe te pas (B8). Die grond van die ander behandeling het tydens deurslaan ‘n besproeiing ontvang om die GWI tot by veldkapasiteit te hervul (B9) en is tydens rypwording weer d.m.v. ‘n DTB strategie besproei. Stokke van die tiende behandeling is tussen bot en deurslaan by ca. 90% PBW onttrekking besproei, gevolg deur besproeiing d.m.v. ‘n gedeeltelike profiel hervul (GPH) strategie tydens rypwording (B10). Om ‘n GPH strategie toe te kon pas, is tussen 40% en 60% PBW ontrekking gehandhaaf. Evapotranspirasie het tussen 3.5 mm/dag en 0.1 mm/dag vir onderskeidelik die natste en droogste behandelings tussen Desember en Februarie gevarieer. Dit was aansienlik laer as volumes wat vir voloppervlak besproeide wingerde benodig word. In die geval van besproeiing by 30% tot 40% PBW onttrekking (B1), 70% tot 80% PBW onttrekking (B4) en ca. 90% PBW onttrekking (B7) deur die loop van die seisoen was die gewasfaktore vir die verwysingverdamping (ETo) 0.4, 0.2 en 0.1 onderskeidelik. Onder die gegewe toestande het die verskillende besproeiingstrategië geen effek op die worteldigtheid en –verspreiding gehad nie. Lootgroei van wingerdstokke wat aan hoë tot baie hoë watertekorte blootgestel was voor deurslaan, het voor middel Desember gestop. Lote van wingerdstokke wat aan hoë tot baie hoë watertekorte voor deurslaan blootgestel is, gevolg deur besproeiing teen ’n hoë frekwensie tydens rypwording, het aktiewe hergroei getoon. Die PBW ontrekkingspeil het sterk in die plantwaterpotensiale van wingerdstokke weerspieël. Blaarwaterpotensiaal is deur heersende klimaatstoestande beïnvloed, terwyl stamwaterpotensiaal minder sensitief teenoor die klimaat was, maar meer direk deur die beskikbaarheid van grondwater beïnvloed is. Vanweë die goeie verband tussen voordagbreek blaar-, mid-dag blaar-, mid-dag stam- en totale daaglikse waterpotensiaal, was dit moontlik om water status van die stokke te her-klassifiseer in terme van vorige vir waterpotensiaalklassifikasies wat op voordagbreek waardes gebasseer is. Waterspanning in B1, B2 en B5 stokke is as geen spanning geklassifiseer, terwyl dié van B7 en B8 voor oes in die hoë tot baie hoë klasse geval het. Hoë frekwensie besproeiing strategieë gedurende rypwording kan suikertoename a.g.v. die groter korrels vertraag. Met die uitsondering van die natste strategie, asook waar stokke volgens die DTB strategie deur die seisoen besproei is, het korrelmassa gedurende rypwording toegeneem. Watertekorte het ’n negatiewe effek op korrelmassa, trosgrootte en produksie gehad. Besproeiingstrategieë waar ’n hoë mate van grondwateronttrekking voor besproeiings toegelaat is, het ’n positiewe effek op die besproeiingwaterproduktiwiteit van wingerd in vergelyking met gereelde besproeiings of ‘n DTB strategie gehad. Watertekorte, veral gedurende rypwording, het ’n verbetering in sensoriese wynkleur en meer prominente wyn aromas, tot gevolg gehad. Besproeiing teen hoë frekwensies gedurende rypwording, het wyne met ’n afgewaterde smaak en aroma karakters asook ’n swak algehele gehalte produseer. Sensoriese wynkleur en spesery karakter die dominante faktore in die bepaling van algehele kwaliteit.

Thesis (MScAgric (Viticulture and Oenology))--University of Stellenbosach, 2010.
ENGLISH ABSTRACT: Cabernet Sauvignon, the most planted red wine cultivar in South Africa, is prone to vigorous growth with low yields. The aim of the study was to describe how Cabernet Sauvignon grapevines react to climate and irrigation within the Swartland region. Such knowledge would assist growers in decisions regarding long term as well as short term cultivation practices. This study was part of a larger project carried out by the Infruitec-Nietvoorbij institute of the Agricultural Research Council at Stellenbosch to determine effects of soil type and climate on yield and wine quality of Cabernet Sauvignon. The larger project was carried out in selected grape growing regions, i.e. Stellenbosch, Swartland, Lower Olifants River and Lower Orange River. Due to the proximity to the Atlantic Ocean, the study area in the Swartland region could be divided into two climatic regions for viticulture. Grapevines near Philadelphia closer to the ocean experienced less water constraints compared to those further inland near Wellington. Variation in stem water potential could also be related to soil water matric potential. Climate tended to have a more pronounced effect on the grapevine response to water constraints further inland than closer to the ocean. Vegetative growth, berry size and yield depended on water constraints experienced by the grapevines. In the warmer climate, severe constraints reduced yield. In the warmer climate, grapes started to ripen earlier than those in the cooler climate. Sugar concentration (mg/mL) was highest where grapevines experienced moderate water constraints. These seemingly balanced grapevines had the highest sugar accumulation, probably due to optimum photosynthesis and carbohydrate utilization. Low water constraints increased vegetative growth which could have been a sink for sugar loading. In addition to sugar loading, degree Balling (°B) increases could also have been due to a concentration effect where water constraints reduced berry volume. Therefore, °B is probably not a representative indicator of grapevine functioning. Anthocyanin biosynthesis, as quantified on a per berry basis, showed that sugar and anthocyanin could be co-regulated, with anthocyanin biosynthesis reaching a plateau when the sugar content per berry reached 200 mg/mL to 220 mg/mL. At véraison, the most intense grape colour occurred where grapevines experienced moderate water constraints, i.e. single drip line at Wellington and no irrigation at Philadelphia. However, at harvest grapes from the cooler climate tended to have more intense colour and higher phenolics, indicating that lower temperatures favoured anthocyanin biosynthesis. These results supported earlier findings that grapevine water status influences berry volume and dynamics of berry ripening. Water constraints tended to increase sensorial wine colour intensity, as well as wine fullness. Moderate water constraints at both localities resulted in the best sensorial wine quality. Yet there were indications that too severe water constraints could be detrimental to wine quality. Irrigation can be used to manipulate grapevine growth in warmer climates, but might be less effective in cooler climates. In warmer climates, moderate water constraints required to achieve balanced grapevine functioning can be obtained with single drip irrigation, but this might not be the case in cooler climates.
AFRIKAANSE OPSOMMING: Cabernet Sauvignon, die mees aangeplante rooiwynkultivar in Suid-Afrika, is geneig tot kragtige groei met lae opbrengste. Die doelwit van hierdie studie was om te beskryf hoe Cabernet Sauvignon-wingerdstokke reageer op klimaat en besproeiing in die Swartland-streek. Hierdie kennis sal kwekers help wanneer hulle besluite moet neem oor langtermyn sowel as korttermyn verbouingspraktyke. Hierdie studie was deel van ‘n groter projek deur die Infruitec-Nietvoorbij Instituut van die Landbounavorsingsraad op Stellenbosch om die effekte van grondtipe en klimaat op die opbrengs en wynkwaliteit van Cabernet Sauvignon te bepaal. Die groter projek is in geselekteerde wingerdverbouingstreke uitgevoer, nl. Stellenbosch, Swartland, Benede Olifantsrivier en Benede Oranjerivier. As gevolg van die nabyheid daarvan aan die Atlantiese Oseaan kon die studiegebied in die Swartland-streek in twee klimaatstreke vir wingerdbou verdeel word. Wingerdstokke by Philadelphia, wat nader aan die oseaan is, het minder waterstremming ervaar as dié verder binnelands naby Wellington. Veranderinge in stamwaterpotensiaal hou moontlik ook verband met die grondwater- matrikspotensiaal. Klimaat het ‘n groter effek op die reaksie van die wingerdstok op waterstremming verder binnelands as nader aan die oseaan. Vegetatiewe groei, korrelgrootte en opbrengs was afhanklik van die waterstremminge wat deur die wingerdstokke ervaar is. In die warmer klimaat het die ernstige stremminge opbrengs verminder. In die warmer klimaat begin druiwe vroeër ryp word as in die koeler klimaat. Suikerkonsentrasie (mg/ml) was die hoogste waar wingerde matige waterstremming ervaar het. Hierdie skynbaar gebalanseerde wingerdstokke het die hoogste suikerakkumulasie vertoon, moontlik as gevolg van optimum fotosintese en koolhidraatverbruik. Lae waterstremming het vegetatiewe groei verhoog, wat ook ‘n vraagpunt vir suikerlading kon wees. Benewens suikerlading kon verhogings in grade Balling (°B) ook moontlik aan ‘n konsentrasie-effek toegeskryf word in terme waarvan waterstremming die korrelvolume verminder het. °B is dus moontlik nie ‘n verteenwoordigende indikator van wingerdstokfunksionering nie. Antosianienbiosintese, soos gekwantifiseer op ‘n per-korrel basis, het getoon dat suiker en antosianien saam gereguleer kon word, en dat antosianienbiosintese ‘n plato bereik het wanneer die suikerinhoud per korrel 200 mg/mL tot 220 mg/mL was. By deurslaan het die mees intense druifkleur voorgekom waar die wingerdstokke matige waterstremming ervaar het, d.w.s. enkel druplyn op Wellington en geen besproeiing op Philadelphia. Teen oes was die druiwe in die koeler klimate egter geneig om meer intense kleur en meer fenole te bevat, wat aandui dat laer temperature antosianienbiosintese bevoordeel. Hierdie resultate ondersteun vroeër bevindings dat die waterstatus van die wingerdstok ‘n invloed op korrelvolume en die dinamika van korrelrypwording het. Waterstremming neig om die sensoriese wynkleurintensiteit te verhoog, asook die volheid van die wyn. Matige waterstremming op beide liggings het aanleiding gegee tot die beste sensoriese wynkwaliteit. Tog was daar aanduidings dat waterstremming wat te straf was, nadelig kon wees vir wynkwaliteit. Besproeiing kan gebruik word om wingerdgroei in warmer klimate te manipuleer, maar is moontlik minder effektief in koeler klimate. In warmer klimate kan die matige waterstremming wat benodig is vir gebalanseerde wingerdstokfunksionering, verkry word deur enkel drupbesproeiing, maar dit is moontlik nie die geval in koeler klimate nie.

Thesis (MScAgric)--University of Stellenbosch, 2011.
ENGLISH ABSTRACT: The study was conducted in the Western Cape Province to investigate the effect of soil preparation on selected soil physical properties. This study was necessitated by the negative effects that high soil bulk density has on the growth and production of a vine. Soil preparation in South Africa are applied to remove root limiting layers in the subsoil and to create a larger soil volume for root growth. The question is whether it is always necessary because of the destruction of macropore structure and also the high costs that is involved. The study includes different soil forms, different depths of tillage, different tillage operations and also the change of soil physical properties with time. Soil physical properties that was investigated include, bulk density (cloth method), infiltration (mini disk infiltrometer and double ring infiltrometer), shear strength (pocket vane tester), soil strength (penetrometer) and root distribution (profile wall method). The main finding was that the positive effects of soil preparation were still clear after 25 years. The bulk density, shear strength, penetration resistance and infiltration with the double ring infiltrometer of the deeper soil preparation practices were considerably lower than those of undisturbed soil. Soil preparation shallower than 60 cm recompacted more than the deeper tillage treatments. Hydraulic conductivity with the mini disk infiltrometer yielded mixed results. This was mainly because measurements represented hydraulic conductivity through the whole profile and therefore can be influenced by many factors. Root distribution has increased with depth of tillage and the effect was clear at Nietvoorbij in the deeper (> 60 cm) soil preparation treatments. There were no significant difference between the two soil preparation methods (delve plough and soilmix) at Kanonkop, although the effect of secondary compaction by the soilmix was quite clear. Recompaction over a year was clear in the 2009 and 2010 tillage treatments at Broodkraal. The methods that were used to determine the soil physical properties have all yield good results. At all the sites the tillage treatments generally yielded better results than the undisturbed soils. It was also clear that the longer the time after tillage the smaller become the difference between the tillage treatments and the undisturbed soils. Recompaction did occur and therefore soil preparation might possibly be applied again before new vines wants to be planted.
AFRIKAANSE OPSOMMING: Die studie is in die Wes-Kaap Provinsie gedoen om die effek van grondvoorbereiding op geselekteerde grondfisiese eienskappe te ondersoek. Hierdie studie is genoodsaak deur die nadelige gevolge wat hoë gronddigthede op die groei en produksie van ’n wingerdstok het. Grondvoorbereiding in Suid-Afrika word toegepas om beperkende lae in die ondergrond te verwyder en sodoende ‘n groter grondvolume vir wortelgroei beskikbaar te stel. Die vraag is egter of dit altyd noodsaaklik is weens die vernietiging van voorkeur vloeikanale en die hoë kostes wat daarmee gepaard gaan. Die studie sluit verskillende grondvorms, verskillende dieptes van bewerking en verskillende tipes bewerking in asook hoe die toestande met verloop van tyd verander. Grondfisiese eienskappe wat ondersoek is, sluit in: bulkdigtheid (kluitmetode), infiltrasie (“mini disk” - en dubbelring infiltrometer), skuifsterkte (skroefbladmeter), grondsterkte (penetrometer) en wortelverspreidings (profielwand metode). Die studie is uitgevoer by drie verskillende proeflokaliteite, nl. Nietvoorbij, Kanonkop en Broodkraal. Die vernaamste bevindings was dat die grondvoorbereidingsbehandelings se voordelige effek oor die langtermyn, na 25 jaar, steeds duidelik waarneembaar was. Die bulkdigtheid, skuifsterkte, penetrasieweerstand en infiltrasie met dubbelring infiltrometer van die dieper grondbewerkingspraktyke was aansienlik laer as die kontrole behandelings (onversteurde grond) gewees. Die grondvoorbereidingsaksies vlakker as 60 cm het tot ʼn mate weer herverdig. Hidrouliese geleiding met minidisk infiltrometer het baie wisselvallige resultate opgelewer. Dit is hoofsaaklik omdat die meting die geleiding deur die hele profiel verteenwoordig en daar baie faktore is wat dit kan beïnvloed. Die wortelverspreiding het met diepte van grondbewerking toegeneem en die langtermyn voordelige effek was duidelik by Nietvoorbij in die dieper (> 60 cm) grondvoorbereidingsbehandelings sigbaar. Die twee grondvoorbereidingspraktyke (dolbewerking en “soilmix”) by Kanonkop het nie betekenisvol van mekaar verskil nie, alhoewel die effek van sekondêre kompaksie soos veroorsaak deur die “soilmix” implement, duidelik was. Herverdigting oor die tydperk van ’n jaar was duidelik tussen die 2009- en 2010 bewerking by Broodkraal. Die metingsmetodes waarmee die grondfisiese eienskappe ondersoek is, het almal goeie resultate gelewer. By al die proeflokaliteite het die bewerkingsbehandelings oor die algemeen beter resultate as die kontrole-behandelings (onversteur) gelewer. Hoe langer die tydperk na grondvoorbereiding hoe kleiner was die verskil tussen die bewerkingsbehandelings en die kontrole. Herverdigting het wel voorgekom en daarom sal grondvoorbereiding moontlik weer toegepas moet word wanneer nuwe aanplantings gemaak word.