Effect of post-harvest summer pruning on carbohydrate reserve status, bud break and fertility of Sultanina H5 in the Lower Orange River region.
| dc.contributor.advisor | Avenant, Eunice | en_ZA |
| dc.contributor.advisor | Avenant, J. H. | en_ZA |
| dc.contributor.author | Toolo, Keboneilwe Boitumelo | en_ZA |
| dc.contributor.other | Stellenbosch University. Faculty of AgriSciences. Dept. of Viticulture and Oenology. | en_ZA |
| dc.date.accessioned | 2022-11-24T12:56:02Z | |
| dc.date.accessioned | 2023-01-16T12:47:54Z | |
| dc.date.available | 2022-11-24T12:56:02Z | |
| dc.date.available | 2023-01-16T12:47:54Z | |
| dc.date.issued | 2022-12 | |
| dc.description | Thesis (MScAgric)--Stellenbosch University, 2022. | en_ZA |
| dc.description.abstract | ENGLISH ABSTRACT: Carbohydrate reserves produced from photosynthesis are stored in perennial tissues of the grapevine in the form of starch and free-sugar fractions or soluble sugars, mostly sucrose, glucose, and fructose. These reserves are highly affected by viticultural practices altering the source-sink relationship in the grapevine. Post-harvest pruning is a practice widely applied by several table grape producers in South Africa aiming to channel carbohydrate reserve accumulation to the remaining shoots. Due to the high input costs of table grape production, any manipulation, including post-harvest summer pruning, should be applied only if it is scientifically proven to have practical and economic benefits. This study, comprising of two trials, aimed to determine whether post-harvest pruning results in increased carbohydrate reserve status, improved bud break and fertility, as well as to establish a base for quantifying and practically assessing the carbohydrate reserve status of grapevines. The first trial focused on establishing the seasonal dynamics of non-structural carbohydrate (NSC) reserves of Vitis vinifera L. cv. Sultanina H5 in the semi-arid Lower Orange River (LOR) and the Mediterranean Hex River Valley (HRV). Root, trunk, cane and/or shoot tissues were sampled monthly and analysed for NSC. The Anthrone method was used to analyse soluble sugars and starch, while enzymatic analysis was used to quantify specific sugars (sucrose, d-fructose and d- glucose). Starch and sucrose were the most abundant forms of NSC in all tissues in both regions. In both regions, soluble sugars in permanent tissues (roots, trunks, canes) reached their highest concentration during dormancy (June-July). The starch concentration was low in all tissues in winter (July), during grapevine dormancy, whereafter it increased to a peak occurring in August (before bud break). A steep decrease in starch concentration was recorded from dormancy to flowering in both regions, indicating a dependency of the vine on carbohydrate reserves during that period. Accumulation of NSC reserves began after flowering to the post-harvest period, reaching their second peaks in autumn. The overall higher soluble sugars and starch (roots and canes) concentrations in the tissues of the Mediterranean region is ascribed to the earlier accumulation of reserves, lower crop load and a shorter post-harvest period characteristic of this region. A basis was established for sampling grapevine tissues for qualitative assessment of grapevine NSC reserve status, linking sampling time to occurrence of peaks in soluble sugars and starch concentrations. It is recommended that sampling for qualitative assessment of soluble sugars should be done after leaf fall, during dormancy (June-July under the conditions of this study). Starch concentrations should be assessed before bud break (August under the conditions of this study). Based on significant positive correlations between NSC concentrations of different tissue types, tissue types that could be sampled for indication of the overall NSC status of the grapevine were identified. Canes and shoots could be sampled and analysed to indicate the overall NSC reserve status of the vine. These tissues are considered the most practical tissue types to sample for determination of grapevine NSC reserve status. The second trial investigated the effect of post-harvest summer pruning applied in the semi-arid Lower Orange River region on NSC reserve status, bud break and fertility of Sultanina H5 grapevines. Five post-harvest pruning treatments were applied, namely an early 33% and a 66% shoot removal pruning treatment one day after harvest (33_1dAH and 66_1dAH respectively), a late 33% and a 66% shoot removal pruning treatment 45 days after harvest (33_45dAH and 66_45dAH respectively) and a control (Ctr), in which no post-harvest summer pruning was applied. To quantify pruning severity, the number and length of removed shoots, as well as the number of leaves and leaf area removed were determined at the time of the post-harvest summer pruning treatment application. After winter pruning was applied, the removed canes and shoots were measured to calculate the overall shoot length and leaf area removed per vine. The day after pruning treatments were applied, photosynthetically active radiation (PAR), as well as photosynthetic activity and related physiological parameters were measured. Cane and/or shoot, stem and root tissue, were sampled on 4 dates for assessing the effect of pruning treatments on NSC reserve status. Bud break and fertility were assessed through forced bud break and bud dissection for potential bud break and fertility, while actual bud break and fertility were assessed in the vineyard. Post-harvest pruning proved to be beneficial for light penetration, but it did not improve the photosynthetic rate of the leaves. A few significant differences were recorded on the impact of the treatments on TNC. These however, do not show a clear trend. Post-harvest summer pruning did not have a significant effect on final bud break and potential fertility of grapevines in the season following the treatment. Based on this one season’s results, post-harvest pruning did not have overall practical benefits. Repeating the treatments for two more seasons on the same data vines, would indicate whether there is a carry-over effect of the practice on NSC, bud break and fertility. It is recommended that in a further phase of this project, available rapid and accurate methods to quantify carbohydrate reserves should be used and/or evaluated for use in grapevine studies, including Near-Infrared spectroscopy, as well as the starch iodine test (already commercially used in the apple and forestry industries). | en_ZA |
| dc.description.abstract | AFRIKAANSE OPSOMMING: Koolhidraatreserwes geproduseer deur fotosintese, word gestoor in permanente strukture van die wingerdstok, in die vorm van stysel en ongebonde suikerfraksies, of oplosbare suikers, meestal sukrose, glucose en fruktose. Hierdie reserwes word grootliks beïmvloed deur wingerdboukundige praktyke wat die bron-vraagpuntbalans in die wingerdtsok verander. Na-oes snoei is ‘n praktyk wat algemeen toegepas word deur verskeie tafeldruiprodusente, met die doel om koolhidraatreserwe-akumulasie te kanaliseer na die oorblywende lote. Weens hoë insetkostes van tafeldruifproduksie, moet enige manipulaise, insluitend na-oes somersnoei, slegs toegepas word, indien daar wetenskaplik bewys is dat dit praktiese en ekonomiese voordele het. Die doel van hierdie studie, bestaande uit twee proewe, was om (i) te bepaal of na-oes snoei lei tot verhoogde koolhidraatreserwestatus, verbeterde bot en vrugbaarheid; en (ii) ‘n basis te vestig vir kwantifisering en praktiese assessering van die koolhidraareserwestatus van wingerdstokke. Die eerste proef het gefokus op die vasstelling van die seisoenale patroon van nie-strukturele koolhidraat (NSK) reserwes van Vitis vinifera L. cv. Sultanina H5 in die semi-ariede Benede Oranjriviergebied (BOR) en die Mediterreënse Hex River Vallei (HRV). Wortel-, stam-. winterloot-en/of groenlootweefsels is maandeliks gemonster en ontleed vir NSK. Die Anthrone metode is gebruik om oplosbare suikers en stysel te ontleed, terwyl ensiematiese ontleding gebruik is om spesifieke suikers te kwantifiseer (sukrose, d-fruktose en d-glukose). Stysel was die vorm van NSK wat die meeste voorgekom het in alle weefsels in beide gebiede. In beide gebiede, het die oplosbare suikers in die permanente weefsel (wortels, stamme, winterlote) hul hoogste konsentrasie tydens dormansie bereik (Junie-Julie). Die styselkonsentrasie was laag in alle weefsels in die winter (Julie), tydens dormansie, waarna dit toegeneem het tot ‘n piek in Augustus (voor bot) in alle permanente weefsels in die Semi-ariede gebied (wortels, stamme en winterlote) en in winterlote en wortels van die Mediterreënse gebied. ‘n Skerp afname in styselkonsentrasie het voorgekom vanaf dormansie tot blom in beide gebiede, wat dui op die afhanklikheid van die wingerdstsok van koolhidraatreserwes gedurende daardie periode. Akkumulasie van NSK reserwes het begin vanaf na blom en gestrek tot in die na-oesperiode, met bereiking van ‘n tweede piek in die herfs. Die algehele hoër styselkonsentrasies in die weefsels van die Semi- ariede gebied gedurende na-oes periode, word toegeskryf aan die langer na-oes periode waartydens gunstige toestande vir fotosintese heers, naamlik ‘n langer fotoperiode, hoër temperature en stralingsvlakke, in vergelyking met die koeler, Mediterreënse gebied. ‘n Grondslag is gelê vir monsterneming van wingerdweefsel vir kwalitatiewe assessering van wingerd NSK reserwestatus, deur die monsternemingtyd te koppel aan die voorkoms van pieke in oplosbare suiker- en styselkonsentrasies. Dit word aanbeveel dat monsterneming vir kwalitatiewe assessering van oplosbare suikers gedoen moet word na blaarval, tydens dormansie (Junie-Julie onder die toestande van hierdie proef). Monsterneming vir assessering van styselkonsentrasie moet voor bot (Augustus onder die toestande van hierdie proef) gedoen word. Op grond van die betekenisvolle interaksies tussen NSK konsentrasies van verskillende weefseltipes, is weefseltipes wat gemonster kan word vir bepaling van die algehele NSK status van die wingerdstok geïdentifiseer. In die Semi-ariede gebied, kan enige van die bogrondse weefseltipes gemonster en ontleed word vir bepaling van die algehele NSK status van die stok. In die Mediterreënse gebied kan enige van die weefseltipes ontleed word vir stysel, terwyl groenlote en winterlote ontleed kan word vir bepaling van oplosbare suikers. Groenlote en/of winterlote word beskou as die mees praktiese weefseltipes om te monster vir bepaling van die wingerstok se NSK reserwestatus. In die tweede proef is die effek van na-oes somersnoei op NSK reserwestatus, bot en vrugbaarheid van Sultanina H5 in die semi-ariede Benede-Oranjeriviergebeid ondersoek. Vyf na- oes snoeibehandelings is toegepas, naamlik ‘n vroeë 33% en ‘n 66% lootverwydering snoeibehandeling een dag na oes (33_1dAH en 66_1dAH onderskeidelik), ‘n laat 33% en ‘n 66% lootverwydering snoeibehandeling 45 dae na oes (33_45dAH en 66_45dAH onderskeidelik) en ‘n kontrole (Ctr), waar geen na-oes somersnoei toegepas is nie. Ten einde die strafheid van snoei te kwantifiseer, is die aantal en die lengte van die lote, asook die aantal blare en die blaaroppervlak wat verwyder is, bepaal direk nadat die na-oes somersnoeibehandeling toegepas is. Nadat wintersnoei toegepas is, is die lote wat verwyder is ook gemeet, om totale lootlengte wat per stok verwyder is, te bepaal. Die dag na toepassing van die na-oes somersnoeibehandelings, is fotosintetiese aktiewe radiasie (FAR) en fotosintese gemeet. Winter- en/of groenloot-, stam- en wortelmonsters is op vier datums gemonster om die effek van snoeibehandlings op NSK reserwestatus te bepaal. Bot en vrugbaarheid is geassesseer deur middel van geforseerde bot en oogontledings vir potensiële bot en vrugbaarheid, terwyl werklike bot en vrugbaarheid in die wingerd geëvalueer is. Na-oes somersnoei het ligindringing deur die lower bevorder, maar dit het nie fotosintese bevorder nie. Na-oes somersnoei het geen betekenisvolle effek gehad op NSK reserwes, bot en vrugbaarheid in die seisoen wat gevolg het op die seisoen waartydens behandelings toegepas is nie. Op grond van hierdie een seisoen se resultate, het na-oes somersnoei nie enige praktiese voordele nie, behalwe verbeterde ligindringing. Herhaling van die behandelings vir twee verdere seisoene op dieselfde datastokke, behoort aan te dui of daar ‘n oordragingsefeek van hierdie praktyk op NSK, bot en vurgbaarheid is. Dit word aanbeveel dat, in ‘n verdere fase van hierdie projek, beskikbare vinnige en akkurate metodes vir kwantifisering van koolhidraatreserwes gebruik en/of geëvalueer moet word vir gebruik in wingerstudies, insluitend Naby-Infra-Rooi spektroskopie, asook die jodiumtoets vir stysel (wat reeds kommersieel in die appel- en bosboubedrywe gebruik word). | af_ZA |
| dc.description.version | Masters | en_ZA |
| dc.format.extent | 128 pages : illustrations (some color) | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/10019.1/126058 | |
| dc.language.iso | en_ZA | en_ZA |
| dc.publisher | Stellenbosch : Stellenbosch University | en_ZA |
| dc.rights.holder | Stellenbosch University | en_ZA |
| dc.subject | Carbohydrates | en_ZA |
| dc.subject | Grapes -- Climatic factors -- Economic aspects -- South Africa - | en_ZA |
| dc.subject | Plants -- Assimilation | en_ZA |
| dc.subject | Non-structural carbohydrates (NSC) | en_ZA |
| dc.subject | Sultanina (Grape) -- Pruning -- South Africa -- Lower Orange River region | en_ZA |
| dc.subject | Table grapes -- South Africa -- Lower Orange River region | en_ZA |
| dc.subject | Table grapes -- Postharvest technology | en_ZA |
| dc.subject | UCTD | en_ZA |
| dc.title | Effect of post-harvest summer pruning on carbohydrate reserve status, bud break and fertility of Sultanina H5 in the Lower Orange River region. | en_ZA |
| dc.type | Thesis | en_ZA |
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