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A.G. Reynolds and D.A. Wardle

Paclobutrazol (PB) soil drenches applied at 0, 10, 20, 30, 40, or 50 mg·liter-1 to potted Vitis vinifera L. `Pinot noir' vines inhibited extension growth of shoots on untopped vines and growth of lateral shoots on topped vines. Internode length, leaf area, and cane maturity were also reduced by the PB soil drenches. Foliar application of gibberellic acid (GA3) appeared to remove the effects of PB on the length of some internodes. Chemical name used: β[(4-chlorophenyl)methyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).

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Andrew G. Reynolds and Douglas A. Wardle

Nine wine grape cultivars [`Chardonnay', `Gewurztraminer', `Ortega', `Riesling', `De Chaunac', `Marechal Foch', `Okanagan Riesling', `Seyval blanc', and Verdelet'], own rooted or grafted to four rootstocks [`Couderc 3309' (Vitis riparia × V. rupestris); `Kober 5BB' (5BB), `Teleki 5C', and `Selektion Oppenheim 4' (SO4) (V. riparia × V. berlandieri)] were planted into a randomized complete block experiment in 1985. Data were collected on yield components, weight of cane prunings (vine size), and fruit composition between 1989 and 1996. Yield per vine, clusters per vine, cluster weight, and berry weight were not affected by rootstock, but SO4 tended to produce lowest berries per cluster. Lowest vine size was associated with 5BB and own-rooted vines were usually largest; 5BB was also associated with highest crop load (yield to vine size ratio). Own-rooted vines tended to produce berries with lowest percentage soluble solids (%SS) while 5BB led to highest %SS. Titratable acidity was not strongly affected and pH differences between rootstocks were very small. These data suggest that rootstocks may not provide significant advantage over own-rooted vines under conditions found in the arid regions of the Pacific northwestern U.S. and British Columbia.

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Andrew G. Reynolds, Margaret Cliff, Douglas A. Wardle, and Marjorie King

Eighty-five cultivars, selections and clones from European winegrape (Vitis spp.) breeding and selection programs were evaluated between 1993 and 1995 in a randomized complete-block experiment. These included Vitis vinifera clones from France as well as Freiburg, Geisenheim, and Weinsberg, Germany. Small yield and fruit composition differences were found amongst the 'Chardonnay' clones. The standard Prosser clone produced wines with highest earthy aroma and acidity and with lowest perfumy aroma, body and finish; Dijon clones 76 and 96 were most perfumy and least vegetal. `Pinot noir' clones also differed somewhat in terms of yield and fruit composition; `Samtröt', `Gamay Beaujolais', and clone Q1342-01 were amongst the most highly colored clones. These clones also tended to have the most intense berry and currant aromas as well as berry, cherry, and currant flavors. These aforementioned clones appear to be highly adaptable to viticultural regions where low heat units during fruit maturation presently limit industry growth.

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Andrew G. Reynolds, Margaret Cliff, Douglas A. Wardle, and Marjorie King

Eighty-five cultivars, selections and clones of winegrapes (Vitis) from European breeding and selection programs were evaluated between 1993–95 in a randomized completeblock experiment. These included selections from Alzey, Freiburg, Geilweilerhof, Geisenheim, Weinsberg, and Würzburg (Germany); Hungary; and the former USSR. Vines were grown under an organic management regime that included sodium silicate sprays for powdery mildew (Uncinula necator) control and oil + detergent for insect control but with little to no nitrogen or other nutritional inputs. The Weinsberg cultivars Heroldrebe and Helfensteiner showed promise viticulturally and sensorially as alternatives to `Pinot noir'. Cultivars from Geisenheim (`Gm 7117-10' and `Gm 7117-26') and Würzburg (`Cantaro' and `Fontanara') appeared promising as `Riesling' alternatives; many displayed similar sensory characteristics to `Riesling', along with reasonable viticultural performance. Cultivars selected at Alzey (`Faberrebe'), Freiburg (`Nobling'), and Weinsberg (`Holder') displayed sensory characteristics superior to the standard cultivar Müller-Thurgau, with very intense muscat, pear, fig, and spicy aromas and flavors. Several muscat-flavored Hungarian white wine cultivars appeared to be superior viticulturally and sensorially to the standard `Csabagyongye'; these included `Kozma Palne Muscotaly', `Zefir', and `Zengo'. Miscellaneous red wine cultivars that showed promise included Geilweilerhof cultivar Regent, and Hungarian selections Kozma 55 and Kozma 525. Vine yields decreased substantially in the 3-year evaluation period, primarily due to lack of nitrogen. Many of these cultivars appeared to be highly adaptable to viticultural regions where cold winters and low heat units during fruit maturation presently restrict cultivar choices.

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Andrew G. Reynolds, Douglas A. Wardle, and Marjorie Dever

Vitis vinifera L. cultivars Müller-Thurgau, Muscat Ottonel, Gewürztraminer, and Kerner were studied for 1 year to document changes in fruit terpene levels from berry stage to free-run and press-juice stages. Substantial amounts of free volatile terpenes (FVTs) and potentially volatile terpenes (PVTs) were lost between berry and juice stages. PVTs were higher in press juices of `Gewürztraminer' and `Muscat Ottonel' than in free-run juices. In another experiment, juices from `Miiller-Thurgau', `Muscat Ottonel', `Kerner', `Optima', `Pearl of Csaba', and `Siegerrebe', harvested 10 to 20 days after a designated initial harvest date, contained higher FVTs and PVTs than initially. A third experiment with `Kerner', `Müller-Thurgau', `Optima', and `Siegerrebe' found highest FVTs and PVTs in juices from grapes subjected to skin contact compared with grapes crushed and immediately pressed. Sensory evaluation showed aroma differences between wines from free-run and press juices of `Miiller-Thurgau' and `Muscat Ottonel', aroma and flavor differences due to harvest date for all cultivars except `Pearl of Csaba', and aroma and flavor differences due to skin contact for `Siegerrebe'.

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Andrew G. Reynolds, Douglas A. Wardle, Brian Drought, and Robert Cantwell

Own-rooted, glasshouse-grown `Chardonnay' vines (Vitis vinifera L.) were planted in a sand medium to which was added one of five levels of granular Gro-Mate (GM), a commercial humate (0, 8, 16, 32, 64 g/pot; 0 to 35 g a.i./pot). Two other treatments consisted of weekly (1× W) or twice-weekly (2× W) applications of liquid GM, whose cumulative addition over the 28 weeks of the experiment totaled 6.7 and 13.4 g a.i., respectively. Shoot length responded to increasing level of GM in a predominantly cubic fashion, with 32 g/pot resulting in the longest shoots. Fresh and dry weights of leaves, shoots, and roots, as well as leaf count and area, exhibited increasing linear or quadratic trends in response to increased level of granular GM. GM increased soil organic matter, K, Ca, Mg, Fe, Mn, Cu, Na, and S and also increased petiole Fe and lamina P, K, and Fe. Liquid treatment resulted in lower soil pH, organic matter, bulk density, and Fe and higher soil conductivity, NO3, P, K, Mg, Cu, Zn, Na, and S than the granular treatments, as well as higher petiole and lamina N and K, lower petiole and lamina P, and lower petiole Zn. Compared to the 1× W treatment, the 2× W produced lower soil bulk density and higher P, lower lamina K, Mn, and Fe; lower petiole Mn; and higher petiole Cu. Plant tissues contained extremely high levels of Mn irrespective of treatment, whereas liquid treatments resulted in high soil NO3 levels. Although liquid GM cannot be recommended for young grapevines under an application regime such as described here, preplant applications of granular GM may have potential for improving growth of young vines in coarse-textured soils. High granular or excessive liquid applications may result in leaf necrosis and retarded growth.

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A.G. Reynolds, D.A. Wardle, A.C. Cottrell, and A.P. Gaunce

Paclobutrazol (PB) was sprayed on hedged `Riesling' (Vitis vinifera L.) vines at one of five concentrations (0, 1000, 2000, 3000, or 4000 mg·liter-1) as single annual applications over 3 years (1987-89). Observations were made on growth, yield, and fruit composition during the years of application and 1 year thereafter (1990) to test carryover effects. PB had no effect on vine vigor, expressed as weight of cane prunings, during the three application years, but reduced vine vigor linearly with concentration in 1990. Yield was reduced by PB in the first 2 years of the trial, while in one season cluster weight and berries per cluster were also reduced. °Brix was increased by PB during all 3 years of application; titratable acidity was reduced and pH increased in the first year of application. PB sprays significantly reduced lateral shoot length, mean leaf size on both main and lateral shoots, and total leaf area on main and lateral shoots. Winter injury to buds, cordons, and trunks was also reduced with increasing PB level. Residues of PB in fruit in the first year of application ranged from 9 μg·kg-1 at the 0-m·gliter-1 level to 638 μg·kg-1 at the 4000-mg·liter-1 level. PB shows promise as a viticultural tool for advancement of fruit maturity, with possible additional benefits such as improved vine winter hardiness. Chemical name used β -[(4-chlorophenyl) methyl]-α -dimethylethyl)-1-H-1,2,4-triazole-l-ethanol (paclobutrazol, PB).

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A.G. Reynolds, M.J. Bouthillier, D.A. Wardle, and L.G. Denby

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A.G. Reynolds, M.J. Bouthillier, D.A. Wardle, and L.G. Denby

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A.G. Reynolds, C.G. Edwards, D.A. Wardle, D.R. Webster, and M. Dever

`Riesling' grapevines (Vitis vinifera L.) were subjected for 4 years (1987-90) to three shoot densities (16, 26, and 36 shoots/m of row) combined with three crop-thinning levels (1, 1.5, and 2 clusters/shoot) in a factorialized treatment arrangement. Weight of cane prunings per vine (vine size) decreased linearly with increasing shoot density and clusters per shoot. Cane periderm formation (in terms of percent canes per vine with >10 ripened internodes) was inhibited by increased shoot density, while vine winter injury (primarily bud and cordon) increased slightly in a linear fashion with increasing clusters per shoot. Canopy density and leaf area data suggested that fruit clusters were most exposed to sunlight at a shoot density of 26 shoots/m of row due to reduced lateral shoot growth and a trend toward slightly smaller leaves. Yield, clusters per vine, and crop load (yield per kilogram of cane prunings) increased with increasing shoot density and clusters per shoot, while other yield components (cluster weight, berries per cluster, and berry weight) decreased. Soluble solids and pH of berries and juices decreased with increasing shoot density and clusters per shoot, but titratable acidity was not substantially affected. Free volatile terpenes increased in berries and juices in 1989 with increasing shoot density, as did potentially volatile terpenes in 1990. Shoot densities of 16 to 26 shoots/m of row are recommended for low to moderately vigorous `Riesling' vines to achieve economically acceptable yields and high winegrape quality simultaneously.