Both the physiological and biochemical control of budburst in the grapevine, Vitis Vinifera L. were investigated. It was found that the accuracy of a predictive model for grapevine budburst based on ambient temperature was limited under the experimental conditions. There was a significant correlation of 4.7 ± 0.3 days between the days of maximal xylem exudation and budburst over the 3 years of investigation. The co-relationships between daily xylem exudate volume and a range of environmental parameters were considered. It was found that soil temperature was highly correlated against daily xylem exudation. Ambient temperature and soil moisture were significantly correlated with xylem exudation, however the coefficients of correlation were much lower than that of soil temperature. Rainfall showed only a very limited correlation with daily xylem exudate flow. Seasonal variations in the pH and the carbohydrate and inorganic nutrient concentrations of xylem exudate were investigated. Exudate carbohydrate concentrations fell from 660 µM before the day of maximal xylem exudation to zero levels within 4 weeks. Xylem exudate pH was found to consistently fall to a minimum at the time of maximal exudate flow. Exudate concentrations of the metallic cofactors Ca, K, Mg, Mn and Zn varied directly with daily exudate flow, suggesting some sort of flow-dependent mobilisation of these nutrients. A growth promontory oligosaccharide fraction was prepared by partial acid hydrolysis of grapevine primary cell wall material. This fraction significantly increased control growth of the Lemna minor L. bioassay over a limited ‘window’ of bioactivity. A growth inhibitory oligosaccharide fraction, similar in activity to abscisic acid was isolated from grapevine xylem exudate prior to budburst. The exudate concentration or efficacy of this substance declined after budburst such that there was no apparent growth inhibition. A model is proposed for grapevine budburst whereby an oligosaccharide growth inhibitor is gradually removed from the xylematic stream under the effects of soil temperature, allowing the surge of metabolic activity and vegetative growth that constitute budburst.

This study concerns the isolation, characterisation and physio-chemical properties of 8,8-methylmethine-(epi)catechin-malvidin-3-glucoside compounds found in red wines. 8,8-Methylmethine-(epi)catechin-malvidin-3-glucoside compounds were isolated via chromatographic methods developed in this study. The compounds were characterised via nuclear magnetic resonance spectrometry which, with the aid of molecular modelling, afforded their possible 3-dimensional structures. Their physio-chemical properties including ionisation and hydration constants, colour parameters and chemical stabilities were determined. The formation of 8,8-methylmethine-flavan-3-ol-malvidin-3-glucoside compounds and other pigments in wines was also studied. 8,8-Methylmethine-(epi)catechin-malvidin-3-glucoside compounds were also synthesised by condensing malvidin-3-glucoside with (epi)catechin in the presence of acetaldehyde. Diastereomers of 8,8-methylmethine-(epi)catechin-malvidin-3-glucoside pigments were isolated from the reaction using size-exclusion liquid chromatography followed by cation-exchange liquid chromatography. The structures of the four 8,8-methylmethine-catechin (and epicatechin)-malvidin-3-glucoside diastereomers were determined using mass spectrometry and one and two-dimensional nuclear magnetic resonance spectroscopy. It was found that for all four compounds, the methylmethine bridge occurs at the 8-positions of malvidin-3-glucoside and (epi)catechin and that the 3-dimensional structural differences between the diastereomers is the positioning of the (epi)catechin moiety with respect to the glucoside group. One diastereomer has the (epi)catechin on the same side, with respect to the malvidin entity whilst it is on the opposite side for the other diastereomer. The proposed structures also afforded the malvidin entity protection from nucleophilic attack via steric hindrance by the (epi)catechin moiety. 8,8-Methylmethine-(epi)catechin-malvidin-3-glucoside pigments have greater colour stability with regards to changes in pH and SO2 bleaching compared to malvidin-3-glucoside providing evidence that little or no hydration in aqueous solutions is occurring for these compounds. Further evidence for little or no hydration occurring is the presence of isosbestic points in the UV-vis spectra observed for the 8,8-methylmethine-(epi)catechin-malvidin-3-glucoside in the pH range 2 to 7. Although the 8,8-methylmethine-(epi)catechin-malvidin-3-glucoside pigments have greater colour stability to pH, SO2 and oxidation, compared to malvidin-3-glucoside, they have lower temporal stabilities and under both aerobic and anaerobic conditions they have significantly higher degradation rate constants than malvidin-3-glucoside. The ionisation constants of the 8,8-methylmethine-(epi)catechin-malvidin-3-glucoside compounds were determined using high voltage paper electrophoresis (HVPE) and UV-visible spectroscopy. The first ionisation constants (pKa1) of the 8,8-methylmethine-(epi)catechin-malvidin-3-glucoside compounds were found to be higher than that of malvidin-3-glucoside whereas the second and third ionisation constants (pKa2 and pKa3) were found to be lower. The correlation of the ionisation constants between HVPE and UV-visible spectroscopy supports the proposal that there is little or no occurrence of hydration for the 8,8-methylmethine-(epi)catechin-malvidin-3-glucoside compounds in the pH range investigated. 8,8-Methylmethine-flavan-3-ol-malvidin-3-glucoside compounds were the major pigments formed during fermentations of chemically defined grape juice media containing malvidin-3-glucoside and various flavan-3-ols. The yeast strain used for fermentation had a major influence on the levels and rates of formation of these pigments during fermentation. The yeast strain used also has an important influence on wine pigment composition, concentration and evolution during maturation thereby affecting the colour density and hue of the resultant wines. The initial formation of 8,8-methylmethine-flavan-3-ol-malvidin-3-glucoside compounds and their subsequent gradual degradation during maturation, allowed a pool of malvidin-3-glucoside to be available for the formation of other colour stable and more temporally stable pigments. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1339479 / Thesis (Ph.D.) - University of Adelaide, School of Agriculture, Food and Wine, 2008

Includes bibliographical references (leaves 158-180) / xiii, [220] leaves : ill. (col.), maps ; 30 cm / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 2002

" August 2002." / Bibliography: leaves 218-235. / viii, 235 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The pathogenicity of Phomopsis taxon 1 is examined in relation to symptom expression and bud loss on grapevines. Phomopsis taxon 1-specific DNA probe, pT1P180, and taxon 2-specific probe, pT1P25, were used to detect Phomopsis taxon 1 and Phomopsis taxon 2 in infected buds, canes and shoots in glasshouse and field experiments. Experiments confirm the isolates of taxon 1 examined did not cause leaf or shoot symptoms associated with Phomopsis cane and leaf spot, and that taxon 2 is more virulent than taxon 1. Suggests that taxon 1 (Diaporthe) is an endophyte which does not cause harm to the grapevine and that chemical control is not warranted for control of taxon 1 on grapevine. / Thesis (Ph.D.)--University of Adelaide, Dept. of Applied and Molecular Ecology, 2002

"November 2002" / Bibliography: leaves 155-176. / xv, 176 leaves : ill. (some col.), plates (col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Studies were conducted to develop soil sampling, detection and quantification techniques for Meloidogyne spp.. (root-knot nematodes, RKN) in vineyards. A survey was conducted in vineyards of South Australia (SA) to validate a DNA based quantification method for RKN and to determine the population structure fo RKN across the grapevine growing areas of SA. The effect of different RKN densities on vine growth during their establishment was also determined. / Thesis (Ph.D.)--University of Adelaide, Dept. of Applied and Molecular Ecology, 2003

Bibliography: leaves 82-89. Rampion mignonette is an annual to short-lived perennial agricultural weed from the Mediterranean region, first found in vineyards at Clare, South Australia, in 1986. The biology and ecology of rampion mignonette was studied to provide a basis for its integrated control and management. The study includes a literature review, maps of world and Australian distribution and drawings showing plant habit and details. A field survey found that rampion mignonette showed little migration and that containment and population reduction could be achieved by careful management including both chemical and cultural techniques. Common herbicides were also found to be effective in controlling the weed. An experiment established that it is unlikely to become a major weed of broadacre crops and pastures in the South Australian dryland farming system. It does however have the potential to compete with grapevines and reduce grape yields.

An important disease of Vitis vinifera production in Oregon and all other commercial growing regions is powdery mildew of grape, caused by the obligate fungal pathogen Uncinula necator (Schwein.) Burril. Grape production can be characterized as a long-term investment in the establishment and maintenance of the vineyard. Establishment times have been reduced with the use of plastic vine shelters, but powdery mildew disease pressure within vine shelters had been an unaddressed issue. Control of the pathogen requires frequent spray applications and costly cultural management of the grape canopy. Industry interest in forecasting programs have shown promise in regulating spray applications to times when they are most effective, or needed. The timing of when to begin spray programs is believed to be a point of weakness in the forecasting programs currently available for grape powdery mildew. The influence of vine shelter use on the development of powdery mildew was investigated in the field during the 1998 and 1999 growing season. Industry standard installations of various brands of vine shelters were tested against modified installations for both incidence and severity of Uncinula necator infection. The industry standard installation of 76 cm high tubes hilled with 8 cm of soil at the bottom to prevent airflow, were effective in reducing the incidence of powdery mildew in both field seasons. Disease reduction was associated with prolonged temperatures above 36��C and the exclusion of infective spores by the artificial barrier created by the vine shelters. The effectiveness of three forecasting programs for predicting the initial spray application was investigated for three seasons. Actual disease onset dates were determined by using trap leaves or plants. The forecasting programs consistently predicted initial spray dates between 31 and 44 days prior to the detection of powdery mildew with the trapping system. Modifications to the existing forecasting programs were attempted to adjust the forecasting programs to more closely predict the actual detected disease onset dates. The UC-Davis program performed the best over the three years of the study, but improvements will be necessary for an adequate forecasting program in the region. Flag shoots were reported for the first time in Oregon. / Graduation date: 2000

Sequence-specific PCR markers were derived from one new and eight previously identified random amplified polymorphic DNA (RAPD) markers for the purpose of identifying grape (Vitis) rootstocks. The markers were developed because the RAPD assay was found to be inconsistent and the original RAPD markers unreliable. Southern hybridization analysis of the RAPD gels with cloned RAPD bands as probes revealed deficiencies of scoring RAPD bands based solely on ethidium bromide staining. In one case, bands of the same size generated by the same primer in different rootstocks -- normally scored as the same marker -- failed to cross-hybridize, implying a lack of homology between the bands. In another case, a band scored as absent based on ethidium bromide staining was detected by hybridization. One of nine RAPD bands was cloned in the present study. All nine were partially sequenced and sequence-specific pairs of primers were synthesized for each for use under stringent PCR conditions. Three of the primer pairs generated products only from the rootstocks from which the original RAPD bands had been cloned; three others produced products from additional rootstocks while still generating polymorphisms; two others generated apparent length variants from some accessions; and one primer pair resulted in a loss of polymorphism. Based on the eight polymorphic markers, five of nine rootstocks could be unambiguously distinguished. / Graduation date: 1996

Geographic Information System (GIS) based computer applications are becoming increasingly popular for delivering, visualizing and analyzing spatial databases. Driven by advances in computing technologies, GIS applications are increasingly used by non- GIS experts as knowledge support tools that allow instant access and visualization of spatial data across the internet. The American Viticultural areas of Texas (AVATXIS) is an example of a web-based GIS tool that we have developed to help viticulturists better understand wine growing regions in Texas. The application allows users to spatially query and visualize a range of edaphic and climatic factors that influence vine growth and grape production. By providing growers a wide variety of climatic and edaphic data sets and an intuitive, easy to use interface for visualizing and downloading this data, AVATXIS serves as an effective tool for characterizing the Texas wine regions. Research in the field of viticulture states that ?Climate governs whether grapes will survive and ripen, what varieties do best where, and some of the characteristics of the resulting wines?. For AVATXIS, a number of specific climate indices critical to wine production were identified through the current viticulture literature and by consulting with experts. These indices include monthly summaries of maximum, minimum and mean temperature, precipitation and Growing Degree-Days (GDD). Publicly available climate data was used to create novel GIS layers for each of these indices. Similarly the importance of soil type to vine growth is recognized, but its relationship to wine quality remains controversial. Publicly available soil data were used to create GIS layers representing simple soil indices (pH, soil texture, depth to bedrock, permeability, available water capacity, and bulk density) useful to the wine grower. These climate and soils data form the central database used by AVATXIS. The intuitive, user interface allows any combination of these GIS layers to be rapidly retrieved and visualized through a standard web-browser by any user of the AVATXIS system.

Thesis (M.S.)--California Polytechnic State University, 2009. / Title from PDF title page; viewed on February 3, 2010. Major professor: W. Keith Patterson, Ph.D. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Agriculture." "November 2009." Includes bibliographical references (p. 68-70).