Thesis (MScAgric)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Thompson Seedless and Regal Seedless are two white seedless table grape cultivars widely produced in South Africa. Both cultivars are susceptible to berry browning, especially Regal Seedless. Browning leads to annual financial losses for table grape growers. Although a correlation between harvest maturity and the occurrence of browning seems to exist, it is still unclear whether maturity levels are the actual contributing factor. The aim of the study was to establish if harvest maturity and crop load could influence the occurrence of browning of both cultivars. The impact of harvest maturity and crop load on phenolic compound concentration in the berry skin of both cultivars was also investigated. Total external browning of Regal Seedless and Thompson Seedless occurred in much higher percentages than internal browning. Regal Seedless showed a tendency to decreased total external browning with harvest maturity. The main reason for this is that net-like browning, which is the greatest contributor to total external browning, decreased with harvest maturity, in all three seasons. External browning of Thompson Seedless increased with harvest maturity in both seasons. Contact browning was the greatest contributor to total external browning of Thompson Seedless. Crop load did not significantly influence berry browning of Regal Seedless or Thompson Seedless grapes. The flavan-3-ol concentration (catechin, epicatechin, procyanidin B1 and procyanidin B2) in Regal Seedless generally increased with harvest maturity, whereas in Thompson Seedless the general tendency was a decrease in the flavan-3-ol concentration with harvest maturity. The development of phenolic compound concentration with maturity could not be correlated with the occurrence of berry browning. Crop load did not affect flavan-3-ol concentration. When the flavan-3-ol concentration of Regal Seedless and Thompson Seedless were compared at different harvest maturities the concentrations of flavan-3-ols were clearly much higher in the skin of Regal Seedless than in the skin of Thompson Seedless (for both the 2008 & 2009 seasons). Comparison of the browning incidence with harvest maturity for these two cultivars (see above) clearly reveals that external browning of Regal Seedless occurred in much higher percentages than on Thompson Seedless. Regal Seedless had much higher levels of external browning than Thompson Seedless. The concentration of flavan-3-ols in the skin of white seedless cultivars may be an indication of the cultivar’s susceptibility to external browning. / AFRIKAANSE OPSOMMING: Thompson Seedless en Regal Seedless is twee wit pitlose tafeldruif kultivars wat ekstensief in Suid-Afrika verbou word. Verbruining kan ‘n probleem wees by beide kultivars, spesifiek Regal Seedless. Die faktore wat aanleiding gee tot verbruining is nog nie duidelik bepaal nie. Alhoewel dit lyk of daar ‘n korrelasie tussen rypheidsgraad van die oes en verbruining kan wees is dit steeds onduidelik of oesrypheidsvlakke die werklike oorsaak van verbruining is. Die doel van die studie was om vas te stel of die rypheidsgraad van die oes en oeslading verbruining van beide kultivars kan beïnvloed. Die effek van oes rypheidsgraad en oeslading op konsentrasie van fenoliese verbindings in die korrelskil van beide kultivars is ook ondersoek. Totale eksterne verbruining van Regal Seedless en Thompson Seedless het in baie hoër persentasies voorgekom as interne verbruining. Daar was ‘n tendens by Regal Seedless dat totale eksterne verbruining verminder het soos die oes ryper geraak het as gevolg van netagtige verbruining, wat die grootste bydrae tot totale eksterne verbruining veroorsaak het. Netagtige verbruining se voorkoms het verminder oor al drie seisoene. Eksterne verbruining van Thompson Seedless het toegeneem met oes rypheid in beide seisoene. Kontak verbruining het grootste byrdae gelewer tot totale eksterne verbruining van Thompson Seedless. Oeslading het nie ‘n betekenisvolle invloed op verbruining van Regal Seedless en Thompson Seedless gehad nie. Die flavan-3-ol (katesjien, epikatesjien, prosianidien B1 en prosianidien B2) konsentrasie van Regal Seedless het met oes rypheid toegeneem. By Thompson Seedless was daar ‘n afname in die flavan-3-ol konsentrasie met oes rypheid. Daar was geen korrrelasie tussen die konsentrasie van fenoliese verbinding en die voorkoms van verbruining vir beide kultivars. Oeslading het nie ‘n betekenisvolle effek op die konsentrasie van fenoliese verbindings gehad nie. Vergelyking van die flavan-3-ol konsentrasie van Regal Seedless en Thompson Seedless by verskillende rypheidsgrade wys dat die konsentrasie baie hoër in die korrel skil van Regal Seedless as in die van Thompson Seedless (vir beide 2008 & 2009 seisoene). Die vergelyking van die voorkoms van verbruining met oesrypheid van beide kultivars wys duidelik dat eksterne verbruining van Regal Seedless in baie hoër persentasies voorkom as in Thompson Seedless. Flavan-3-ol konsentrasie in die skil van wit pitlose kultivars kan ‘n aanduiding wees van die kultivar se moontlike risiko vir die voorkoms van eksterne verbruining.

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2018-09-25T17:50:35Z No. of bitstreams: 1 2016 - Miqu?ias Permanhani.pdf: 8462509 bytes, checksum: 23e7a0fff474c07ddaca0105da127c59 (MD5) / Made available in DSpace on 2018-09-25T17:50:35Z (GMT). No. of bitstreams: 1 2016 - Miqu?ias Permanhani.pdf: 8462509 bytes, checksum: 23e7a0fff474c07ddaca0105da127c59 (MD5) Previous issue date: 2016-09-29 / CAPES / ?BRS Vit?ria? is the first seedless grape cultivar launched by Embrapa Grape and Wine with tolerance to downy mildew (Plasmopora viticola), in addition to presenting high fertility of buds and a special flavor similar to raspberry but its clusters are compact, which requires the establishment of specific management techniques to reduce compactness. Two trials were conducted in the northwestern S?o Paulo state aiming to evaluate the agronomic performance of ?BRS Vit?ria? grapevine grafted onto different rootstocks, as well as the effect of shoots and/or clusters tipping together with the application of gibberellic acid (GA3) on production and characteristics of fruits. In the first experiment, the treatments were constituted by the combination of ?BRS Vitoria? grapevine grafted onto rootstocks ?Paulsen 1103?, ?Kober 5BB?, ?IAC 766? and ?IAC 572?, while in the second trial four tipping modalities (control or without tipping, shoots, clusters, shoots + clusters) were done in the end of flowering stage, associated or not with the GA3 application (0 and 30 mg L-1) when berries had 6-8 mm of diameter. It was verified that the period from beginning of ripening to harvest of clusters had greater influence in the production cycle (from pruning to harvest) of scion/rootstock combinations, presenting longer and shorter interval, respectively, when grafted onto ?IAC 766? and ?Paulsen 1103?. There was obtained higher production and vegetative vigor when grafted onto ?IAC 766? and ?IAC 572?, being that the ?IAC 766? provided the higher average of clusters weight and berries size. The rootstocks did not influence in total soluble solids (TSS) content and titratable acidity (TA) of the berries. In addition, there was no effect of the tipping treatments on production and characteristics of fruits, except for the TSS content, indicating that this technique may not be efficient to reduce clusters compactness of ?BRS Vitoria? grape or that it should not be performed during the flowering period. However, the clusters tipping in association with the use of GA3 allowed a higher average TSS content by reducing the difference between berries at the top and tip of cluster. One single application of GA3 at 30 mg L-1 when berries had 6-8 mm of diameter provided an increase in fruits weight and size but there was no significant effect (p> 0.05) on production and, although it has not caused a negative impact on quality of ?BRS Vitoria? grape, a decrease was observed in TSS content and TSS/TA ratio of the berries. / ?BRS Vit?ria? ? a primeira cultivar de uva sem sementes lan?ada pela Embrapa Uva e Vinho com toler?ncia ao m?ldio (Plasmopora viticola), al?m de apresentar alta fertilidade de gemas e um sabor especial semelhante ? framboesa, por?m seus cachos s?o compactos, o que exige o estabelecimento de t?cnicas espec?ficas de manejo para reduzir a compacidade. Foram conduzidos dois experimentos na regi?o noroeste do estado de S?o Paulo com o objetivo de avaliar o desempenho agron?mico da videira ?BRS Vit?ria? enxertada sobre diferentes porta-enxertos, bem como, o efeito do desponte de ramos e/ou de cachos em conjunto com a aplica??o do ?cido giber?lico (GA3) na produ??o e nas caracter?sticas dos frutos. No primeiro experimento, os tratamentos foram constitu?dos pela combina??o da videira ?BRS Vit?ria? enxertada sobre os porta-enxertos ?Paulsen 1103?, ?Kober 5BB?, ?IAC 766? e ?IAC 572?, enquanto no segundo experimento, foram realizadas quatro modalidades de desponte (testemunha ou sem desponte, ramos, cachos, ramos + cachos) no est?gio de fim do florescimento, associados ou n?o com a aplica??o de GA3 (0 e 30 mg L-1) quando as bagas apresentavam 6-8 mm de di?metro. Foi verificado que o per?odo do in?cio da matura??o ? colheita dos cachos teve maior influencia no ciclo de produ??o (da poda ? colheita) das combina??es copa/porta-enxerto, apresentando intervalo mais longo e mais curto, respectivamente, quando sobre ?IAC 766? e ?Paulsen 1103?. Obteve-se maior produ??o e vigor vegetativo sobre ?IAC 766? e ?IAC 572?, sendo que o ?IAC 766? proporcionou maiores m?dias de massa de cachos e tamanho de bagas. Os porta-enxertos n?o influenciaram no teor de s?lidos sol?veis totais (SST) e acidez titul?vel (AT) das bagas. Al?m disso, n?o houve efeito do desponte na produ??o e nas caracter?sticas dos frutos, exceto para o teor de SST, indicando que essa t?cnica pode n?o ser eficiente para reduzir a compacidade dos cachos de uva ?BRS Vit?ria? ou que n?o deve ser realizada durante o per?odo de florescimento. No entanto, o desponte de cachos associado com o uso do GA3 possibilitou um maior teor m?dio de SST ao reduzir a diferen?a existente entre bagas na parte superior e na ponta do cacho. Uma ?nica aplica??o de GA3 a 30 mg L-1 quando as bagas tinham 6-8 mm de di?metro proporcionou um aumento na massa e no tamanho dos frutos, por?m n?o houve efeito significativo (p >0.05) na produ??o e, embora n?o tenha causado um impacto negativo na qualidade da uva ?BRS Vit?ria?, observou-se uma redu??o no teor de SST e na rela??o SST/AT das bagas.