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Optimising productivity and grape composition (grapevine potential) for a specific wine production goal: adaptation of grapevine reproductive/vegetative balance in modified training systems

dc.contributor.advisorStrever, A. E.en_ZA
dc.contributor.authorBosman, Annelien_ZA
dc.contributor.otherStellenbosch University. Faculty of AgriSciences. Dept. of Viticulture and Oenology.en_ZA
dc.date.accessioned2020-12-01T13:29:59Z
dc.date.accessioned2021-01-31T19:46:12Z
dc.date.available2020-12-01T13:29:59Z
dc.date.available2021-01-31T19:46:12Z
dc.date.issued2020-12
dc.identifier.urihttp://hdl.handle.net/10019.1/109353
dc.descriptionThesis (MScAgric)--Stellenbosch University, 2020.en_ZA
dc.description.abstractENGLISH ABSTRACT: Provided the current economic context in South Africa, grape producers are being forced to think outside the box and explore and employ new approaches in order to optimize productivity in a sustainable way. Optimum productivity is only achievable once a balanced vine is capable of producing its maximum yield at optimum quality, while keeping input costs (i.e. labour) at a minimum. The perception that only low yielding, small vines are capable of producing quality yields contributes to the general reluctance among producers to consider taking actions such as converting existing trellising or training systems to increase vigour and yield. Three training systems (Smart-Dyson, vertically shoot positioned system (VSP) and a reduced canopy treatment), executed in a Vitis vinifera L. cv. Shiraz vineyard located in Stellenbosch were evaluated over the course of three seasons. The purpose was to investigate whether or not the conversion of an existing training system is indeed a viable option to increase productivity in a sustainable way and without negatively impacting on wine quality. In addition to this, the concepts of grapevine balance and compensation were studied to reach scientifically valid conclusions regarding the vine’s compensatory reaction to an alteration in its architecture. This investigation was conducted by converting an existing training system to determine whether it is possible for grapevines to reach maximum productivity (yield) without forfeiting quality. The trial vineyard was characterized by high variability in vigour. After assessing vigour according to historical pruning data, grapevines were divided into high and low vigour categories after which conversion to the altered training systems (treatments) were carried out. The layout of this experiment was a completely randomized block design. Plant and soil water status was monitored, but soil water monitoring was not measured treatment specific, which meant that the exact water requirement on a per treatment basis could not accurately be determined. Vegetative and reproductive measurements were conducted over all three seasons. Pruning and yield data was collected and the yield:pruning mass ratios were determined and compared between the various treatments. Vegetative measurements included primary shoot growth tempo and length, total lateral shoot length, total primary leaf area, total lateral leaf area and total leaf area per vine. In general, a progressive increase in vegetative growth was observed in all treatments as the trial progressed. All the Smart-Dyson treatments displayed a steady increase in yield over the course of the trial. Starting before véraison, berry sampling took place weekly and berry composition was analysed in order to determine ripening progression. Wines from each individual treatment of each season’s harvest were prepared, and the wines made during the first two seasons evaluated by means of qualitative descriptive analysis (QDA). Results obtained from QDA, indicated that no negative parameters were associated with any treatments, thus the conversion effect and increase in vegetative growth and yield had no substantial influence on composition. Instead, all indications were that wine style rather than wine quality was influenced. It was concluded that seasonal effects played a substantial role in the difference in wine styles between seasons. The conversion effect itself played a relatively smaller role when considering that no significant differences in wine attributes between treatments and controls were detected. The decision to modify existing training systems to accommodate larger vigour and increased production is an option that can be seriously considered, since this trial has proven that actions that increase yield do not necessarily mean that quality has to be forfeited.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Gegewe die huidige ekonomiese konteks in Suid-Afrika, word druifprodusente daartoe gedwing om buite die boks te dink en nuwe benaderings te verken en toe te pas, ten einde produktiwiteit te optimaliseer op ʼn volhoubare wyse. Optimale produktiwiteit is slegs haalbaar wanneer ʼn gebalanseerde wingerdstok daartoe in staat is om die maksimum opbrengs teen optimale kwaliteit te produseer, terwyl arbeidskostes en -insette tot ʼn minimum beperk word. Die persepsie dat slegs klein wingerdstokke met lae opbrengste kwaliteit druiwe kan lewer, dra by tot die algemene aarseling onder produsente om aksies te neem soos die omskakeling van bestaande prieel- of opleistelsels, wat sal lei tot ʼn toename in groeikrag en opbrengs. Drie opleistelsels (Smart-Dyson, vertikale lootposisionering sisteem (VSP) en ʼn gereduseerde lower behandeling), uitgevoer in ʼn Vitis vinifera L. cv. Shiraz wingerd in Stellenbosch is geevalueer oor die verloop van drie seisoene. Die doelwit was om ondersoek in te stel na of die omskakeling van ʼn bestaande opleistelsel daadwerklik ʼn lewensvatbare opsie is om produktiwiteit te optimaliseer op ʼn volhoubare wyse, sonder om wynkwaliteit negatief te beïnvloed. Hiermee saam, is die konsepte van wingerdbalans en -kompensasie bestudeer om tot wetenskaplik grondige gevolgtrekkings te kom rakende die wingerdstok se kompensasie reaksie op ʼn verandering in argitektuur. Hierdie ondersoek was ingestel deur die omskakeling van ʼn bestaande opleistelsel om te bepaal of dit moontlik is vir druiwestokke om optimale produktiwiteit (opbrengs) te realiseer sonder om kwaliteit in te boet. Die proef wingerd was gekenmerk deur ʼn hoë variasie in groeikrag. Nadat groeikrag geassesseer is volgens historiese data, is druiwestokke verdeel in hoë en lae groeikrag kategorieë, waarna die omskakeling na die alternatiewe opleistelsels (behandelings) uitgevoer is. Die uitleg van hierdie proef was ʼn totale ewekansige blok ontwerp. Plant- en grondwater status was gemonitor, maar grondwater monitering was nie spesifiek volgens behandelings gemeet nie, wat daartoe gelei het dat die presiese water behoefte op ʼn per-behandeling basis nie akkuraat bepaal kon word nie. Vegetatiewe en reproduktiewe metings was uitgevoer oor al drie seisoene. Snoei- en opbrengsdata was ingesamel en die opbrengs:snoeimassa verhouding was bepaal en vergelyk tussen die verskeie behandelings. Vegetatiewe metings het ingesluit die groeitempo en lengte van hooflote, totale syloot lengte, totale hoofloot blaaroppervlakte, totale syloot blaaroppervlakte en totale blaaroppervlakte per stok. Oor die algemeen was ʼn progressiewe toename in vegetatiewe groei waargeneem in alle behandelings met die verloop van die proef. Alle Smart-Dyson behandelings het ʼn geleidelike toename in opbrengs getoon met die verloop van die proef. Monsterneming van korrels het reeds begin voor deurslaan en is weekliks uitgevoer, waartydens korrel samestelling geanaliseer is om die verloop van rypwording te bepaal. Tydens elkeen van die seisoene is wyne van elke individuele behandeling voorberei, en die wyne geproduseer tydens die eerste twee seisoene was geëvalueer deur die gebruik van kwalitatiewe beskrywende analise (“qualitative descriptive” analysis of “QDA”). Resultate verkry vanaf QDA het aangedui dat geen negatiewe parameters geassosieer was met enige behandelings nie, dus het die omskakelingseffek en toename in vegetatiewe groei en opbrengs geen noemenswaardige invloed op wynkwaliteit gehad nie. Inteendeel, alle aanduidings was dat wynstyl eerder as wynkwaliteit beïnvloed was. Daar is tot die gevolgtrekking gekom dat seisoenale effekte ʼn groot rol gespeel het in die verskil in wynstyle tussen seisoene. Die omskakelingseffek self het ʼn relatiewe klein rol gespeel wanneer daar in gedagte gehou word dat geen noemenswaardige verskille in wyneienskappe tussen die behandelings en die kontroles waargeneem is nie. Die besluit om ʼn bestaande opleistelsel te modifiseer om groter groeikrag en ʼn toename in produksie te akkommodeer, is ʼn opsie wat ernstig oorweeg kan word, aangesien hierdie proef bewys het dat aksies wat lei tot ʼn toename in opbrengs nie noodwendig beteken dat kwaliteit ingeboet moet word nie.en_ZA
dc.format.extent149 pages : illustrations (some color)en_ZA
dc.language.isoen_ZAen_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.subjectGrapevineen_ZA
dc.subjectTraining systemsen_ZA
dc.subjectPlants -- Effect of soil moisture onen_ZA
dc.subjectGrapes -- Breeding -- South Africaen_ZA
dc.subjectQuality of products -- South Africaen_ZA
dc.subjectLabor productivity -- Africa, Southern -- Agricultureen_ZA
dc.subjectFarm management -- Economic aspects -- South Africaen_ZA
dc.subjectCrop yields -- South Africaen_ZA
dc.subjectUCTDen_ZA
dc.titleOptimising productivity and grape composition (grapevine potential) for a specific wine production goal: adaptation of grapevine reproductive/vegetative balance in modified training systemsen_ZA
dc.typeThesisen_ZA
dc.description.versionMastersen_ZA
dc.rights.holderStellenbosch Universityen_ZA


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