Search Results
Abstract
Three-year-old ‘Cardinal’ and ‘Pinot noir’ vines were grown from véraison to fruit maturity in a stationary and rotating phytotron at high (30°C) and low (20°C) day temperatures in combination with both high (>2,500 ft-c) and low (< 1,200 ft-c) average light intensities. Night temperature (6 PM to 6 AM) was 15°C in all treatments. Berries were collected at weekly intervals and analyzed for various constituents.
Low temperature usually resulted in increased berry weight, total acidity, and malate, and in decreased pH, arginine, proline, and total N in the berry juices, as compared to fruits grown at high temperature. The concentrations of total soluble solids and tartrate in the fruits generally did not significantly differ with temperature. Low light intensity at both high and low temperatures generally resulted in reduced berry weight, total soluble solids, pH, and proline, and in increased levels of total acidity, malate, arginine, and total N in the berry juices compared to grapes grown at high light intensity at the same room temperature. The concentration of arginine was highly correlated with the level of total N in the fruits of both cultivars.
Abstract
Three years of observations were made at Oakville, California, on a vineyard trial of 3 pruning severities on 2 scion grape cultivars, Chardonnay and Gamay Beaujolais, grafted onto 2 phylloxera-resistant rootstocks, ‘St. George’ and ‘A × R #1’. There was a marked increase in crop production with decreased pruning severity. With ‘Chardonnay’ on ‘St. George’ there was nearly a 3-fold increase in yield when the pruning went from 5 retained buds/lb. (453.6g) of prunings to 15 buds/lb. With ‘Gamay Beaujolais’, the yield increase approached 2-fold. Vines on ‘A × R #1’ were markedly more fruitful than those on ‘St. George’, and this rootstock difference was not influenced by pruning severity over a 3-year period.
The variability in level of pruning, as estimated from a visual inspection of individual vines, was great. This could account for both low yields and high vine sizes with ‘Chardonnay’. The pruning level used by an experienced pruner was about 8 retained buds/lb. of prunings on average-sized vines of ‘Chardonnay’ on ‘St. George’, and about 6 buds on the largest vines.
The most severe pruning was very restrictive on yields per vine, and vine vigor was enhanced at these low bud counts. Fruit maturity was delayed by the least-severe pruning level and, in some instances, vine size was reduced the following year. Under the conditions of the test site, the intermediate level of pruning severity, 10 buds/lb. of prunings, was appropriate for the small-clustered, cane-pruned cultivars at the intermediate vine sizes.
Abstract
Nonfruiting ‘Thompson Seedless’ grapevine rootings were grown for 30-day periods in phytotron rooms at variable day temp (6:00 AM to 6:00 PM) from 20 to 40°C, in combination with high light (HL,>2,000 ft-c) and low light (LL, <400 ft-c). Night temp in all treatments was 15°C. Maximum total vine growth and net assimilation rate occurred at 30°C under HL and at 20°C under LL. Gain in dry matter per vine was 3- to 18-fold greater under HL than under LL. The level of total carbohydrates (sugars plus starch) in roots of plants grown under HL was also maximal at 30°C. The concn of total carbohydrates in trunk tissues however, varied little with temp from 20 to 35°C, but was significantly (P<0.01) reduced at 40°C. Low light intensity markedly reduced (P<0.01) the levels of sugars and starch in root and trunk tissues compared to the levels in vines grown at HL, regardless of temp.