Littérature scientifique sur le sujet « Viticulture – South Africa – Robertson »

Based on diagnostic samples received at the Agricultural Research Council – Onderstepoort Veterinary Institute (ARC-OVI), a reference centre for African horse sickness (AHS) and bluetongue (BT) for the World Organisation for Animal Health (OIE), the traditional picture on the presence and occurrence of AHS seems to have changed dramatically in South Africa. Outbreaks of AHS virus (AHSV) have increased in this country over the last three to eight years. Outbreaks tend to occur earlier in the season than normally expected. Unpredicted outbreaks of AHS during the past five years in the declared AHS-free area in the South-Western Cape has led to the temporary closure of the quarantine station in Cape Town and the ban on horse exports from South Africa with significant losses to the horse industry as a whole. In January and February 2006, outbreaks of AHSV serotype 9 have also occurred in the George/Knysna area in the Western Cape. Outbreaks in this area occurred over a relatively long period and continued into the colder months of the year. This seems to indicate that AHSV has overwintered in this frost-free area, and that it could have occurred in cycling hosts (donkeys and zebras) and/or in adult Culicoides species. Since 2001, AHS has occurred annually in the Eastern Cape, South Africa, with at least four serotypes in circulation today. In an outbreak in April 2008 in Port Elisabeth, Eastern Cape, C. bolitinos was the dominant species in the coastal areas, whereas C. imicola was the dominant one in the inland area. In the outbreak in February and March 2008 in Robertson and in Kimberley, Northern Cape, C. imicola was the dominant species. Pools of midges have been tested for virus detection during each outbreak. From the outbreak in Robertson, 13 pools were posi­tive for equine encephalosis virus (EEV) and two for BTV. From the outbreak in Kimberley, EEV was isolated from one pool of C. tuttifrutti. The role of C. tuttifrutti as a vector is still poorly understood.

Conventional agriculture has made the search for sustainability urgent, more so with regards to climate change. This has extended to the grape and wine industry, an important industry in South Africa in terms of labor employment and foreign exchange. This paper aims to review the current state of knowledge with regards to the three pillars of sustainability and with regards to climate change. In order to understand sustainability in South Africa, a historical context is needed, because the welfare of farm workers still retains vestiges of past Apartheid. Ecological responsibility and higher profits are the main reasons for sustainable practices. Additionally, water use, chemical use, and soil erosion are important environmental sustainability concerns. With regards to climate change, in terms of economic sustainability, there will be winners and losers and social sustainability issues will intensify as changes occur in farms. Table grape producers are relatively more profitable than wine grape producers. Furthermore, pest, disease, irrigation pressure will worsen as the climate warms. However, there are long- and short-term adaptation strategies such as changes in viticulture practices and grape cultivars, respectively, to stem the effects of climate change, but this may be stymied by cost and farmers’ perceptions of climate change.

Abstract The Regional Atmospheric Modeling System (RAMS) was used to assess local air circulation patterns over the wine-producing Stellenbosch region of South Africa. Numerical simulations using four nested grids (25, 5, and 1 km, and 200 m of horizontal resolution) were performed for each day of February 2000 (during the grape-ripening period) over southern Western Cape Province. Modeled hourly data were extracted from the analysis files and used to produce mean hourly fields (temperature, relative humidity, wind speed, and radiation). Three runs with increasing horizontal resolutions for the finer grid were performed (run 1 with two nested grids of 25 and 5 km; run 2 with three nested grids of 25, 5, and 1 km; run 3 with four nested grids of 25, 5, and 1 km, and 200 m). For each event, the simulations of 1-km and 200-m resolution were superior to the 5-km-resolution simulation, especially in reproducing the local air circulations (sea and slopes breezes) because of a better representation of the local terrain (topography and vegetation cover). The use of a high-resolution grid (200 m) may be of greater value in the identification of potential terrain for viticulture.

Nowadays, table grape consumers prefer seedless grape varieties, so the market promotion of seedless varieties continues at a rapid pace. Responding to consumer preferences, the breeders have developed numerous various-flavour seedless varieties with large berries and bunches. The study purpose is to assess the prospects of cultivation and use in breeding of a new seedless Regal Seedless grape variety bred in South Africa. By origin, this is an intraspecific hybrid of the species V. vinifera L., with an early middle ripening period. The author carried out the variety study to assess agrobiological, economically valuable traits and properties and compiled a short ampelographic description. The study was carried out in 2017–2019 at the experimental vineyard of Ya.I. Potapenko All-Russian Research Institute for Viticulture and Winemaking – Branch of Federal Rostov Agricultural Research Center. The study focuses on non-irrigated covered and grafted vineyards, the Kober 5BB rootstock, the planting pattern of 3 × 1.5 m, and a fan-shaping thankless bush. As to a set of positive parameters (yield, high vendebility, natural seedlessness without the use of gibberellin, large size characteristics, and good taste), the Regal Seedless variety is of certain interest for industrial viticulture, and this variety can also be recommended for use in further breeding as a source of seedless and large berries. According to preliminary studies, the ripened berries of this variety should not be kept long on the bush to prevent peel browning and deterioration in vendebility. The variety is recommended as a highly commercial table grape without the PPP use, but it is not suitable for the production of raisins due to insufficient sugar accumulation. It is recommended that the variety should be grown in areas of sufficient moisture or as an irrigated crop.

The Wacky Wine Festival in Robertson, South Africa, is one of the country’s largest wine festivals. The uniqueness of this wine festival is that it takes place on an existing wine route where 48 wine farms actively participate in the event. Events such as these have long been used to promote a destination or region and its products in order to generate revenue and grow tourism. This paper presents the results of a survey that was conducted during the festival in June 2009 in which 420 questionnaires were completed by visitors to the festival. The aim was to identify the determinants of visitors’ spending at the festival. Factor analysis was applied to differentiate three types of wine tourists: Festinos, Epicureans and Social Adventurists. Consequently, these three groupings and other sociodemographic and behavioural attributes of festival attendees were regressed as independent variables against expenditure in an attempt to refine future marketing strategies. It was the first time that this type of research was conducted at a wine festival in South Africa, and the findings indicated that determinants of visitor spending differ from event to event. Results also showed that a variety of socio-demographic and behavioural determinants influence spending. These include age, days spent at the festival, place of origin and repeat visits. The study also identified the high spending market (“epicureans”) that could assist marketers and event organisers in increasing the economic effects of the event.

In 2003, a glyphosate-resistant plantago (Plantago lanceolata L.) population located in the Robertson district of South Africa was subjected to different glyphosate dosages and the highest dosage (7200 g a.e. ha−1) gave no acceptable levels of control. Here we reconfirm resistance and investigate the mechanism of glyphosate resistance. Dose-response curves indicated that the glyphosate dosage rate causing 50% survival (LD50) for the resistant (R) biotype is 43 times greater than for the susceptible (S) biotype, i.e., 43-fold resistant to glyphosate. Investigation into the molecular mechanism of plantago showed shikimate accumulation of the R biotype was lower than that of the S biotype. The reported 31P and 13C nuclear magnetic resonance (NMR) spectra show rapid glyphosate translocation into the young untreated leaves of the S biotype. No glyphosate translocation was observed in the R biotype. A point mutation in the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene, resulting in an amino acid substitution was also observed, indicating two unique glyphosate resistance mechanisms within the R biotype. The rapid evolution of glyphosate-resistant weeds threatens the usage of the world’s most important herbicide (glyphosate), which is essential in world food production and further limits grower options for weed control. New weed management strategies will be necessary to combat plantago R biotypes.

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.

In recent years, viticulture has seen phenomenal growth, particularly in such countries as Australia, New Zealand, the United States, Chile, and South Africa. The surge in production of quality wines in these countries has been built largely on the practice of good enology and investment in high technology in the winery, enabling vintners to produce consistently good, even fine wines. Yet less attention has been paid to the influence of vineyard conditions on wines and their distinctiveness-an influence that is embodied in the French concept of terroir. An essential component of terroir is soil and the interaction between it, local climate, vineyard practices, and grape variety on the quality of grapes and distinctiveness of their flavor. This book considers that component, providing basic information on soil properties and behavior in the context of site selection for new vineyards and on the demands placed on soils for grape growth and production of wines. Soils for Fine Wines will be of interest to professors and upper-level students in enology, viticulture, soils and agronomy as well as wine enthusiasts and professionals in the wine industry.

In order to prepare our students for a challenging workplace, the Department of Viticulture and Oenology at Stellenbosch University in South Africa have ‘layered’ Engaged Learning strategies throughout the four-year undergraduate degree in an approach that is innovative in a science-based programme. In this research project, we assessed the effects of service-learning (SL) and a six-month internship on student employability by analysing reflections that were collected over a number of years. We also asked industry members whether they felt students had improved in key areas after the final year internship. The student submissions for SL showed evidence of personal growth and transformation, and those for the internship reflected industry requirements for professional skills in a complex and technically demanding milieu. It was found that these engaged experiences provided sound preparation for working life, as well as giving students opportunities for self-questioning and personal growth, which is unusual in the natural sciences learning environment.