One red and one white cultivar of winegrapes grown in Southern Arizona was pruned to four different methods. The red cultivar was 'Merlot' and the white was 'Sauvignon Blanc'. The pruning methods were 2 bud spur, 4 bud spur, cane and basal buds only. The basal bud treatment was eliminated for 'Sauvignon Blanc'. The 4 bud spur method resulted in significantly greater yield when compared to the other methods. Fruit produced from the basal bud only treatment resulted in fruit that was significantly greater in pH and acid content. The 'Sauvignon Blanc' cultivar had significantly higher yield with cane pruning with no difference in fruit quality.

Four year old 'Flame Seedless' grapevines, located in a commercial vineyard, were subjected to increased water stress levels based on infrared canopy temperatures and the Crop Water Stress Index (CWSI) for two years. CWSI levels were approximately .18, .30 and .33 for the wet, medium and dry treatments. In the first year there were no significant differences in yield however, there was a significant reduction in the amount of water applied in both the medium and dry treatments when compared to the wet treatment. In addition, the wet treatment had significantly greater growth during the first growing season when comparing pruning weights.

"Department of Horticulture, Viticulture and Oenology, Faculty of Agriculture and Natural Resource Sciences, The University of Adelaide, Waite Campus, Glen Osmond S.A." Bibliography: leaves 136-149 This investigated focussed on selected aspects of berry development and ripening that were subject to variation. Shiraz and Chardonnay were chosen as experimental varieties because these cultivars presented a large range of variability in the field. The extent of the variation within each of the recorded berry parameters was assessed using the coefficient of variation (CV), a unitless measure of sample variability relative to the sample mean, ideally suited to comparative studies.

Includes a list of publications co-authored by the author during the preparation of this thesis. Bibliography: leaves 103-111. Studies the links between grape composition, wine composition and wine sensory properties. Developed a new method of measuring glycoside concentration in grapes (glycosyl-glucose assay) and a modified measurement of wine colour density in red wine. These were used to analyse samples of Shiraz grapes and wines from a comprehensive vineyard irrigation trial. Glycosyl-glucose concentrations shows promise for the prediction of wine composition and flavor intensity.

Water is a scarce resource worldwide and a particular problem for producers of wine grapes in Australia and Chile where periodic drought severely limits vine growth. Most vineyards in these countries are irrigated and the development of efficient water management practices for vineyards is required. Strategies such as regulated deficit irrigation (RDI) and partial root zone drying (PRD) have been introduced with the objective of maximising the efficiency of water use relative to yield while ensuring that grape quality is not compromised. The problem is that the advantages of these strategies can only be realised if there is accurate information about weather parameters, spatial distribution of soil moisture and vine water use and status. This information can then be used to provide answers for growers to the key irrigation questions of when to irrigate and how much water to apply. The overarching hypothesis of this thesis was than an integrated approach to irrigation scheduling incorporating data on weather, physiological status of the vines and soil wetting patterns is essential to accurately target the narrow range of soil moisture and vine stress thresholds required for realising the advantages of RDI and PRD. The hypothesis was tested through a series of field experiments. The results supported that an integrated approach to irrigation produces the most desirable outcomes in terms of water use and berry quality irrespective of irrigation strategies. The most appropriate way to answer the question of when to irrigate is to measure stem rather than leaf water potential. The question of how much water to apply can readily be answered using a new technique and software developed in this study. It was concluded that PRD is more difficult to manage than RDI because of the complexity pf PRD and the financial and logistic requirements of a double irrigation line. PRD had no effect on crop water use efficiency, berry quality or yield when the same amount of water was applied in the PRD and conventional drip treatments. / Doctor of Philosophy (PhD)

Ochratoxin A (OA), a nephrotoxin and potential carcinogen, has been found in many foods, including grapes and grape products. Limits of 2 μg/kg in wine and 10 μg/kg in dried vine fruit have been introduced by the European Union. This study presents information on the ecology of ochratoxin A production by black Aspergillus spp. in Australian vineyards, and the passage of the toxin throughout winemaking. Aspergillus niger and A. carbonarius were isolated from vineyard soils in 17 of 17, and four of 17 Australian viticultural regions, respectively. A. aculeatus was isolated infrequently. All thirty-two isolates of A. carbonarius and three of 100 isolates of A. niger produced OA. Of Australian A. niger isolates analysed for restriction fragment length polymorphisms within the internal transcribed spacer region of 5.8S ribosomal DNA, 61 of 113 isolates, including the three toxigenic isolates, were of type N pattern, and 52 were type T. A selection of these A. carbonarius and A. niger aggregate isolates, as well as imported isolates, were compared using enterobacterial repetitive intergenic consensus (ERIC)-PCR, amplified fragment length polymorphisms (AFLP) and microsatellite markers. ERIC and AFLP clearly differentiated A. niger from A.carbonarius. AFLP further divided A. niger into types N and T. Six polymorphic microsatellite markers, developed specifically for A. niger, also differentiated strains into N and T types. There was no clear relationship between genotypic distribution and ochratoxigenicity, substrate or geographic origin. The survival of A. carbonarius spores on filter membranes was examined at water activities (aw) 0.4-1.0, and at 1 °C, 15 °C, 25 °C and 37 °C. Survival generally increased at lower temperatures. The lowest water activity, 0.4, best supported the survival of spores, but 0.6- 0.9 aw was often deleterious. Complex interactions between temperature and water activity were observed. Viability of A. carbonarius spores on filter membranes decreased ca 10[superscript 5] fold upon exposure to sunlight, equivalent to 10 mWh of cumulative ultraviolet irradiation at 290-400 nm. Growth and toxin production were examined for five isolates of A. carbonarius and two of A. niger on solid medium simulating juice at early veraison, within the range 0.98-0.92 aw, and at 15 °C, 25 °C, 30 °C and 35 °C. Maximum growth for A. carbonarius and A. niger occurred at ca 0.965 aw / 30 °C and ca 0.98 aw / 35 °C, respectively. The optimum temperature for OA production was 15 °C and little was produced above 25 °C. The optimum aw for toxin production was 0.95 for A. niger and 0.95-0.98 for A. carbonarius. Toxin was produced in young colonies, however, levels were reduced as colonies aged. Black Aspergillus spp. were more commonly isolated from the surface than from the pulp of berries, and increased with berry maturity, or damage. A. niger was isolated more frequently than A. carbonarius and A. aculeatus. Populations of A. carbonarius inoculated onto bunches of Chardonnay and Shiraz decreased from pre-bunch closure to early veraison. Populations from veraison to harvest were variable, and ncreased in bunches with tight clustering and splitting. In a trial with Semillon bunches, omitting fungicide sprays after flowering did not increase the development of Aspergillus rot. Inoculation of bunches with A. carbonarius spore suspension did not necessarily result in Aspergillus bunch rot. In vitro trials suggested that the severity of rot was mediated primarily by the degree of berry damage, followed by the extent of spore coverage. No clear trends regarding cultivar susceptibility were observed. For Semillon bunches inoculated with A. carbonarius spores with and without berry puncture, increased susceptibility to rot and OA formation was associated with berry damage, in particular at greater than 12.3 °Brix (20 d before harvest). OA contamination of bunches was related to the number of mouldy berries per bunch, with shrivelled, severely mouldy berries the primary source of OA. Puncture-inoculation of white grapes (Chardonnay and Semillon) and red grapes (Shiraz) on the vine with A. carbonarius resulted in berries containing OA. Inoculated grapes displayed greater total soluble solids due to berry shrivelling, and greater titratable acidity due to production of citric acid by the fungus. Samples taken throughout vinification of these grapes were analysed for OA. Pressing resulted in the greatest reduction in OA (68-85% decrease in concentration, compared with that of crushed grapes). Additional reductions occurred at racking from grape and gross lees, and after storage. OA was removed by binding to marc, grape and gross lees. Pectolytic enzyme treatment of white must, bentonite juice fining, recovery of juice or wine from lees, and static or rotary style fermentation of red must, had no effect on OA contamination. Bentonite in white wine (containing 56 mg/L grape-derived proteins) and yeast hulls in red wine were effective fining agents for removing OA. Findings from these studies may contribute to the improvement of strategies to minimise OA in Australian wine and dried vine fruit. / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture and Wine, 2005.

"October 2002" / Includes bibliographical references (leaves 172-183) / x, 183 leaves : ill. (some col.) ; 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 Horticulture, Viticulture and Oenology, 2002

Bibliography: leaves 195-209. / xxvi, 209 leaves : ill., ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This study investigated seed development, phenolic composition of seeds and skins, and phenolic composition and sensory properties of wines made from berries of Vitis Vinifera L. cv. Shiraz that were developed and ripened under different levels of sunlight intensity at the bunch zone. The study also examined the relationships between seed and berry development, and the links between berry composition, wine composition and wine sensory properties. / Thesis (Ph.D.)--University of Adelaide, School of Agriculture and Wine, Discipline of Wine and Horticulture, 2004

Bibliography: leaves 129-151. / xiv, 151 [65] leaves : ill. (some col.) ; 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, 1999

Includes a list of publications co-authored by the author during the preparation of this thesis. / Bibliography: leaves 103-111. / vi, 111 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Studies the links between grape composition, wine composition and wine sensory properties. Developed a new method of measuring glycoside concentration in grapes (glycosyl-glucose assay) and a modified measurement of wine colour density in red wine. These were used to analyse samples of Shiraz grapes and wines from a comprehensive vineyard irrigation trial. Glycosyl-glucose concentrations shows promise for the prediction of wine composition and flavor intensity. / Thesis (Ph.D.)--University of Adelaide, Dept. of Horticulture, Viticulture and Oenology, 2001