Thesis (MScAgric)--University of Stellenbosch, 2009. / Bibliography. Also available via the Internet.

Modern canopy management practices and irrigation strategies have improved the economic and environmental sustainability of Australia ' s wine industry, in terms of increased production and improved wine quality for minimal production cost and environmental impact. This study tested the hypothesis that partial rootzone drying ( PRD ) integrated with low input, minimal pruning practices can improve sustainability of winegrape production in warm - climate, irrigated vineyards. The bi - factorial experiment investigated three conventional pruning practices; hand spur pruning ( SPUR ), mechanical hedging ( MECH ) and minimal pruning ( MIN ) integrated with standard drip ( SD ) and PRD irrigation strategies. The sustainability of winegrape production of field - grown cv. Shiraz grapevines was determined by examining yield, fruit composition, wine composition and quality, vine physiology and susceptibility of bunches to Botrytis bunch rot. Winegrape production was strongly influenced by pruning level and the resultant bunch number per vine. Increased node retention at pruning of minimal pruned vines resulted in 4 - fold more bunches per vine than spur pruned vines. Mechanical hedged vines had an intermediate number of bunches per vine. Yield generally reflected the trend in bunch number per vine. However, minimally pruned and mechanically hedged vines compensated for greater carbohydrate partitioning between reproductive sinks by producing smaller bunches with fewer berries per bunch. Partial drying of the grapevine rootzone had a detrimental effect on yield relative to SD irrigation ( 18 % ). The additive effect of SD combined with light pruning treatments resulted in few statistically significant interactions for the measured yield components. Berry weight was the only parameter influenced by the interaction between irrigation and pruning during the three experimental seasons ; PRD + MIN reduced berry weight by 36 % compared to SD + SPUR, in response to lower irrigation inputs and higher bunch number. A 2 - fold increase in water use efficiency ( tonnes per megalitre ) was found by the reduced irrigation inputs of PRD combined with the high crop levels of MIN vines compared to SD + SPUR vines. Fruit and wine composition was also largely unaffected by combined irrigation and pruning treatments, as a result of the additive effect of PRD and MIN. However, light pruning levels ( MIN and MECH ) and their associated small berry size and high bunch exposure, reduced pH and increased titratable acidity, and anthocyanin and phenolic concentrations of berry juice compared to SPUR. Minor pruning level effects on wine composition can be directly correlated with those observed on fruit composition. PRD had minimal effect on basic fruit composition but strong effects on wine spectral parameters : density, hue, total anthocyanin and phenolic concentration and ionised anthocyanin concentration, possibly as a result of co - pigmentation of anthocyanin compounds with exocarp tannins. Berry size was strongly correlated with fruit and wine quality. Small berries ( i.e. from PRD and MIN ) had lower pH and higher anthocyanin and phenolic concentrations in the juice and produced wine that was more acidic, brighter and had higher colour density and anthocyanin ( total and ionised ) and phenolic concentrations than all other treatments. Midday and diurnal leaf gas exchange were manipulated by partially drying the rootzone. PRD reduced midday stomatal conductance, photosynthesis and transpiration compared to SD. Stomatal limitation on photosynthesis and transpiration was probable, given the strong positive relationship with stomatal conductance and reduced carbon isotope discrimination by PRD. Transpiration efficiency was improved for PRD irrigated vines compared to SD irrigated vines. Leaf water potential and osmotic potential were measured diurnally, in conjunction with leaf gas exchange to investigate the response of PRD irrigated vines to increasing vapour pressure deficit. Diurnally, stomatal conductance was reduced by PRD compared to SD, which maintained leaf water potential, while no osmotic adjustment occurred. Therefore, PRD irrigation maintained hydraulic water status by hydrating half of the rootzone, whilst dehydration of the other half of the rootzone resulted in the partial closure of stomata. Pruning treatment effects on vine physiology were less pronounced. Minor gas exchange effects showed that pruning level influenced carboxylation efficiency and not stomatal limitations, as photosynthesis was not directly correlated with stomatal conductance. Bunches were least resistant to infection by Botrytis when fully developed and at maximum maturity. The development of bunches into tighter clusters as berry size increased from veraison to harvest and the increase in sugar content may have encouraged development of Botrytis. The distinct bunch architecture resulting from the combined pruning and irrigation treatments influenced the incidence and severity of Botrytis bunch rot. Light pruning combined with PRD irrigation produced small, loose bunches in season 2001 - 02, which were less susceptible to Botrytis bunch rot development compared to the large, compact bunches produced on SD + SPUR vines. However, low bunch numbers and high fruit - set on MIN and MECH vines in season 2002 - 03 led to a significant change in bunch architecture. As a consequence of the increased compactness of bunches in season 2002 - 03, no pruning effects on Botrytis development were observed. Long term economic and environmental sustainability of winegrape production is dependent on continual improvement in fruit and wine quality, preservation of yield, reduced water and chemical usage. This study has shown partial drying of the rootzone combined with light pruning techniques improved yield, fruit and wine composition, water use efficiency and transpiration efficiency and reduced the incidence and severity of Botrytis bunch rot compared to SD and severe pruning levels. Therefore, over the three experimental seasons, PRD combined with minimal pruning was determined as the preferred strategy to enhance the sustainability of winegrape production of Shiraz cv. in warm - climate, irrigated vineyards. / Thesis (Ph.D.)--School of Agriculture and Wine, 2004.

Thesis (MAgric)--University of Stellenbosch, 2007. / Bibliography. Also available via the Internet.

Good grapes are required to make good wine. Quality wines start in quality vineyards. Vineyard design, installation, and operation, including site location, trellis options, vine selection, and canopy management, along with when to harvest are discussed. While winemaking is the final phase in the pursuit of the winemaker's passion, it is but a simple formula. The beginning of a good wine is in a good vineyard. This study includes a financial projection for a 10-acre vineyard as well as for starting an onsite, complementary sized winery. Even though many small-to-medium vineyards-to-wineries have started over the last decade, the reason to enter into this type of business is not profit, but passion. Profits are relatively small for the time and labor investment, but the unique wine creations that result are amazing, for the winemaker and the one who enjoys the result.

Thesis (MScAgric)--University of Stellenbosch, 2005. / Bibliography. Also available via the Internet.

Heat induced protein haze is a common problem in white wine. Grape derived pathogenesis related proteins slowly denature and aggregate during wine storage and this gives rise to light dispersing haze. Protein haze formation is currently prevented by removing proteins using bentonite, an aluminium silicate clay, but this method has drawbacks. A potential alternative or complementary method is the use of haze protective factors ( HPF ), specific mannoproteins from Saccharomyces cerevisiae that visually reduce protein haze. Hpf1p was originally isolated from Muscat Gordo Blanco wine and Hpf2p from a synthetic grape juice ferment. Based on partial amino acid sequences, putative structural genes, HPF1 and HPF2, for these proteins were identified. HPF1 has a homologue, HPF1 ', ( 71 % similarity ) in S. cerevisiae. Sequence analysis suggests that Hpf1p, Hpf1 ' p and Hpf2p are localised to the cell wall or plasma membrane. This study aimed to determine the biological function of the HPF genes in S. cerevisiae. HPF overexpression and deletion strains were constructed and analysed for cell wall related phenotypes. Under a number of conditions, including cold temperature and ethanol stress, the hpf1 Δ hpf1 ' Δ strain was more tolerant than the wild type strain. However, mating efficiency of the hpf1 Δ hpf1 ' Δ strain was significantly less than the wild type strain and this was found to be correlated with the persistence of a septum between the mating partners. The decreased mating efficiency was also mating type specific, only occurring in MAT α cells. This study also aimed to establish conclusively that the HPF genes do indeed encode proteins with haze protective properties. Haze protective activity of the material from ferment supernatants was assessed. Material from the HPF deletion strains exhibited significantly less haze protective activity than the wild type. Moreover, material derived from HPF1 and HPF1 ' overexpressors was more active than material from the wild type. A 6xHis - tagged Hpf2p was expressed and purified using immobilised metal affinity chromatography. This Hpf2p had significant haze protective activity. Modification of N - glycans of 6xHis - Hpf2p by Endoglycosidase H decreased its haze protective activity.visually reduce protein haze. Hpf1p was originally isolated from Muscat Gordo Blanco wine and Hpf2p from a synthetic grape juice ferment. Based on partial amino acid sequences, putative structural genes, HPF1 and HPF2, for these proteins were identified. HPF1 has a homologue, HPF1 ', ( 71 % similarity ) in S. cerevisiae. Sequence analysis suggests that Hpf1p, Hpf1 ' p and Hpf2p are localised to the cell wall or plasma membrane. This study aimed to determine the biological function of the HPF genes in S. cerevisiae. HPF overexpression and deletion strains were constructed and analysed for cell wall related phenotypes. Under a number of conditions, including cold temperature and ethanol stress, the hpf1 Δ hpf1 ' Δ strain was more tolerant than the wild type strain. However, mating efficiency of the hpf1 Δ hpf1 ' Δ strain was significantly less than the wild type strain and this was found to be correlated with the persistence of a septum between the mating partners. The decreased mating efficiency was also mating type specific, only occurring in MAT α cells. This study also aimed to establish conclusively that the HPF genes do indeed encode proteins with haze protective properties. Haze protective activity of the material from ferment supernatants was assessed. Material from the HPF deletion strains exhibited significantly less haze protective activity than the wild type. Moreover, material derived from HPF1 and HPF1 ' overexpressors was more active than material from the wild type. A 6xHis - tagged Hpf2p was expressed and purified using immobilised metal affinity chromatography. This Hpf2p had significant haze protective activity. Modification of N - glycans of 6xHis - Hpf2p by Endoglycosidase H decreased its haze protective activity. / Thesis (Ph.D.)--School of Agriculture and Wine, 2003.

Made available in DSpace on 2016-12-08T15:50:03Z (GMT). No. of bitstreams: 1 PGMS12DA010.pdf: 3217381 bytes, checksum: 345dcfe3caa8168fae0e2fe64e17df72 (MD5) Previous issue date: 2012-02-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The wine industry has been expanding its participation in the economy of the Planalto Sul Santa Catarina. The soil and climate are two important factors in defining the composition of grapes for winemaking. This study aimed to evaluate the spatial and temporal variability of the chemical, physical and soil water storage elevation and assess what are the conditions that foster productivity and composition of wine grapes. The experiment was conducted in a commercial vineyard, located in São Joaquim (SC), Cfb type climate, subtropical (mesothermal) in a Pachic Humudepts and a Typic Dystrudepts in yields between 2008 and 2011. The variety was Cabernet Sauvignon, established in 2003, grafted on Paulsen in 1103 and conducted cordon training system, shady. Each soil in a grid with 37 points, samples were collected for determination of physical and chemical properties of soil. Soil moisture was measured periodically in two seasons. At each point were collected bunches of grapes to determine their physical, physico-chemical and phenolic compounds. Data were submitted to exploratory analysis, geostatistics, analysis of variance (ANOVA) and Pearson linear correlation. Means were compared by "t" test. The soil type and its position in the landscape influence the spatial variability of physical and chemical properties of soils in the vineyards of altitude. There is spatial variability of chemical and physical attributes in the two Inceptisols, classified as medium to high for the physical attributes and high and very high for the chemical. In Pachic Humudepts variability water storage is less than the Typic Dystrudepts, and is more water available to the vines. The Typic Dystrudepts, with better drainage produces grapes with the most suitable composition to the making of fine wines, while the Pachic Humudepts in years with higher rainfall has negatively affected the composition of the grape. The physical and physico-chemical properties of the grape are dependent on soil and climate, with more pronounced effect of climate / A vitivinicultura vem expandindo a sua participação na economia da região do Planalto Sul Catarinense. O solo e o clima são dois fatores importantes na definição da composição da uva para vinificação. O presente trabalho objetivou avaliar a variabilidade espacial e temporal de atributos químicos, físicos e o armazenamento de água de solos de altitude e avaliar quais são as condições que favorecem a produtividade e a composição das uvas viniferas. O experimento foi realizado em um vinhedo comercial, localizado em São Joaquim (SC), com clima do tipo Cfb, subtropical (mesotérmico), em um Cambissolo Húmico e um Cambissolo Háplico, nas safras entre 2008 a 2011. A variedade foi a Cabernet Sauvignon, implantada em 2003, enxertada sobre Paulsen 1103 e conduzida no sistema de condução espaldeira, sob sombrite. Em cada solo, em uma malha com 37 pontos, amostras foram coletadas para a determinação dos atributos físicos e químicos do solo. A umidade do solo foi determinada periodicamente, em duas safras. Em cada ponto foram coletados cachos de uvas para a determinação de suas características físicas, físico-químicas e compostos fenólicos. Os dados foram submetidos à análise exploratória, geoestatística, análise de variância (ANOVA) e correlação linear de Pearson. As médias foram comparadas pelo teste t . O tipo de solo e sua posição na paisagem influenciam a variabilidade espacial dos atributos físicos e químicos dos solos nos vinhedos de altitude. Há variabilidade espacial dos atributos químicos e físicos nos dois Cambissolos, classificada em média a alta para os atributos físicos e alta e muito alta para os atributos químicos. No Cambissolo Húmico a variabilidade do armazenamento de água é menor do que no Cambissolo Háplico, e tem mais água disponível para as videiras. O Cambissolo Háplico, com melhor drenagem produz uva com composição mais adequada à elaboração de vinhos finos, enquanto o Cambissolo Húmico em anos de maior pluviosidade tem a composição da uva afetada negativamente. As características físicas e físico-químicas da uva são dependentes do solo e do clima, com efeito mais pronunciado do clima