Progress 09/11/06 to 09/30/10
Outputs
Progress Report Objectives (from AD-416) 1) Evaluate whether rootstocks alter winegrape fruit composition during ripening and at harvest compared with winegrapes grown on their own roots. 2) Test for interactions between winegrape variety (scion) and rootstock in terms of fruit composition. Approach (from AD-416) Conduct a field experiment with three winegrape varieties (Merlot, Syrah, Chardonnay) that are either grown on their own roots or grafted to six different rootstocks. Fruit samples will be collected weekly from veraison through harvest from each variety/rootstock combination, weighed and analyzed for soluble solids, pH, titratable acidity, and color using standard laboratory practices. Documents Grant with Washington State University. Formerly 5358-21000-034-20G (12/2008). Although phylloxera does not pose an immediate threat to the wine industry in eastern Washington, it is the most significant insect pest of wine grapes throughout the world. Since it cannot be controlled by chemical or biological means, grafting susceptible wine grapes onto tolerant rootstocks is the only long-term insurance against this devastating root pest. Some rootstocks also provide resistance to nematodes that may reduce vineyard longevity and fruit quality, but it is not clear if the rootstocks themselves alter grape composition and, ultimately, wine quality. The performance of three winegrape varieties on five rootstocks or on their own roots was evaluated in the WSU-IAREC rootstock block with ten field replicates. At harvest, the grapes with adjacent field replicates were combined to make five winemaking replicates. Wines were made at the Prosser IAREC research winery in variable capacity stainless steel tanks (volume 100-300 L). The study took place over three vintages (2007-2009). The grape variables we measured were Brix, titratable acidity, pH, potassium (skin, seeds, and pulp), tannins (skin and seeds), and anthocyanins. Variables measured for wine were ethanol, titratable acidity, pH, potassium, tannins, total iron reactive phenolics and anthocyanins. We found that grape variety and vintage were the most significant variables in this experiment and rootstock did not ultimately alter fruit or wine composition. We found that rootstock had little or no effect on any of the grape or wine composition variables that we measured over our 3-year study. The primary statistically significant variables identified in this study were the variety and vintage. Methods of ADODR monitoring included meetings, e-mail, and phone calls.
Impacts
(N/A)
Publications
|
Progress 10/01/08 to 09/30/09
Outputs
Progress Report Objectives (from AD-416) 1) Evaluate whether rootstocks alter winegrape fruit composition during ripening and at harvest compared with winegrapes grown on their own roots. 2) Test for interactions between winegrape variety (scion) and rootstock in terms of fruit composition. Approach (from AD-416) Conduct a field experiment with three winegrape varieties (Merlot, Syrah, Chardonnay) that are either grown on their own roots or grafted to six different rootstocks. Fruit samples will be collected weekly from veraison through harvest from each variety/rootstock combination, weighed and analyzed for soluble solids, pH, titratable acidity, and color using standard laboratory practices. Documents Grant with Washington State University. Formerly 5358-21000-034-20G (12/2008). Significant Activities that Support Special Target Populations Although phylloxera is not an immediate threat to vineyards in eastern Washington it still remains the most significant threat to vines in the world. No chemical or biological means of controlling the pest exist. Resistant rootstocks have been grafted to achieve not only resistance to phylloxera, but also nematodes. Unfortunately it is not clear if grafted vines under eastern Washington soil and climatic conditions will have similar fruit composition as own rooted vines. Information on grafted vine performance will be important should the situation arise that grafting is necessary. The objective of this project was to determine the effects of rootstock and scion combinations on fruit ripening and composition at harvest. A field experiment was conducted with three wine grape varieties (Merlot, Syrah, Chardonnay) that were either grown on their own roots or grafted to five different rootstocks. The findings show primarily small differences in wine and grape composition between own-rooted and grafted vines. The inherent differences between cultivars were also observed. After two years of work, the differences observed between own-rooted and grafted vines appear to be subtle. It is inconclusive at this stage but speculatively it seems that rootstocks should pose no immediate problem in terms of the most abundant classes of compounds including sugar, organic acids, tannins, anthocyanins or potassium in both grapes and wine. Methods of ADODR monitoring included meetings, e-mail, and phone calls.
Impacts
(N/A)
Publications
|
Progress 10/01/07 to 09/30/08
Outputs
Progress Report Objectives (from AD-416) 1) Evaluate whether rootstocks alter winegrape fruit composition during ripening and at harvest compared with winegrapes grown on their own roots. 2) Test for interactions between winegrape variety (scion) and rootstock in terms of fruit composition. Approach (from AD-416) Conduct a field experiment with three winegrape varieties (Merlot, Syrah, Chardonnay) that are either grown on their own roots or grafted to six different rootstocks. Fruit samples will be collected weekly from veraison through harvest from each variety/rootstock combination, weighed and analyzed for soluble solids, pH, titratable acidity, and color using standard laboratory practices. Documents Grant with Washington State University. Significant Activities that Support Special Target Populations This is the second year of a multi-year project and already we are seeing some progress. The crop yield data showed that own-rooted Chardonnay tended to have greater yields than grafted vines, while no clear differences were observed for Merlot. Own-rooted Syrah had the lowest yields and 3309-Syrah grafts were the highest. For Chardonnay and Merlot the rootstocks did not influence sugar and color accumulation, nor the rate of acid decline. As a contrast, own-rooted Syrah ripened fastest, and Syrah-140-2 had significantly lower color. Own-rooted Chardonnay and Merlot consistently had the highest pH during ripening. For the finished wines, own-rooted Chardonnay had the highest pH and lowest titratable acidity. For the most part, Merlot wines showed no differences except 1103P and 140R, which had the greatest titratable acidity. Own-rooted Syrah had the highest pH and second highest titratable acidity while Syrah grafted to 3309 had the lowest pH and highest titratable acidity. In contrast to last year, all of the rootstock scion combinations were high in proline and low in arginine. Only Syrah had significant amounts of arginine and had relatively lower amounts of proline than the other two varieties. The wines were made under modest conditions (25 gallon garbage cans) and moderate success was gained throughout the process. Within a variety, there were no observed differences in the alcohol concentration for any of the wines produced. All of the red wines were evaluated for their tannin, anthocyanins, and total iron reactive phenolics content at pressing. The results show that for Merlot there are no significant differences between any of the phenolic components. For Syrah there were no significant differences for the tannins and total phenolics; however, some small detectable differences were seen with anthocyanins. The rootstocks 101-14, 1103 P, and 5C had significantly greater anthocyanins than the other rootstocks and own-rooted vines. We did not observe greater concentrations in polymeric pigments for any of the Syrah wines (data not shown). It is well known that polymeric pigments are formed via reactions with tannins and various other phenolics and organic acids. The lack of greater polymeric pigments in the wines with significantly greater anthocyanin concentrations suggests that tannin and total iron reactive phenolics, which were not different, play a significant role in polymeric pigment formation. Thus, to stabilize pigment you must have greater amounts of tannins to stabilize the color; otherwise, it may be lost. Generally, Syrah had significantly greater concentrations of anthocyanins than Merlot wines but also had significantly less tannin and iron-reactive phenolics than the Merlot wines. In the current season, we will be making separate lots of wine from each scion/rootstock combination. We also hope to demonstrate if differences exist in wines made from such combinations and, in particular, if grafting is able to alter wine composition and if significant differences exist sensory analysis will be performed. Methods of ADODR monitoring included meetings, e-mail, and phone calls.
Impacts
(N/A)
Publications
|
Progress 10/01/06 to 09/30/07
Outputs
Progress Report Objectives (from AD-416) 1) Evaluate whether rootstocks alter winegrape fruit composition during ripening and at harvest compared with winegrapes grown on their own roots. 2) Test for interactions between winegrape variety (scion) and rootstock in terms of fruit composition. Approach (from AD-416) Conduct a field experiment with three winegrape varieties (Merlot, Syrah, Chardonnay) that are either grown on their own roots or grafted to six different rootstocks. Fruit samples will be collected weekly from veraison through harvest from each variety/rootstock combination, weighed and analyzed for soluble solids, pH, titratable acidity, and color using standard laboratory practices. Documents Grant with Washington State University. Significant Activities that Support Special Target Populations This report serves to document research conducted under a grant agreement between ARS and Washington State University. Additional details of research can be found in the report for the parent project 5358-21000-034- 00D, Production Systems to Promote Yield and Quality of Grapes in the Pacific Northwest. Dr. Harbertson and collaborators conducted the following research towards the agreements objectives: Own-rooted Chardonnay tended to have higher yields than grafted vines, while no clear differences were found for Merlot, and own-rooted Syrah had the lowest yields and Syrah grafted to 3309 had the highest. The rootstocks had no influence on sugar and color accumulation and acid degradation in Chardonnay and Merlot. On the other hand, sugar accumulation was fastest on the (undercropped) own-rooted Syrah, and less color accumulated on Syrah grafted to 140-2. Throughout ripening, Chardonnay and Merlot, but not Syrah, consistently had the highest pH on their own roots (Merlot also on 101-14) and the lowest on 140-2. The color of Merlot juice decreased as berry size increased, but this was not true for Syrah. Although there was no significant rootstock effect on juice potassium (K+) content, the difference in pH between and within varieties was in large part explained by variations in K+ rather than titratable acidity: Merlot contained the most and Chardonnay the least K+. Proline and arginine were by far the dominant amino acids present in grape juice, and there were marked differences among varieties: Merlot juice was high in praline but low in arginine, Syrah was low in proline but high in arginine, while Chardonnay was low in both amino acids. Juice from own-rooted Chardonnay and Syrah, but not Merlot, contained considerably more arginine than did juice from grafted vines. This is of practical significance, since musts deficient in arginine may result in sluggish or stuck fermentations. Grafting did not affect juice proline. In the current season we will be making separate lots of wine from each scion/rootstock combination. We hope to demonstrate if differences exist in wines made from such combinations and, in particular, if grafting is able to alter wine composition and sensory perception. Therefore, wines will be made for three years, and sensory analysis will be performed along with chemical analyses of these wines. ADODR Statement: The ADODR met with the cooperating PI and project personnel at meetings during the year and discussed results through phone calls, e-mail, and in person.
Impacts
(N/A)
Publications
|
|