Location: Horticultural Crops Research2009 Annual Report
1a. Objectives (from AD-416)
Objective 1: Determine effects of water management on wine grape productivity and fruit maturity. Objective 2: Integrate the development and use of analytical methods for the evaluation of phenolic compounds and other chemical indicators of quality in fruit, fruit products, and wine. Objective 3: Determine effects of vineyard and vine microclimate on fruit development, vine productivity, and fruit quality, particularly phenolic compounds.
1b. Approach (from AD-416)
Our fundamental approach for conducting the proposed research is based on interdisciplinary work toward grape production systems and connecting production practices to the quality of the harvested fruit or value-added fruit products. Although each team member is responsible for a distinct experimental focus, overall goals and responsibilities of the contributors overlap because the interactions among system processes and properties transcend disciplines. Formerly 5358-21000-034-00D (11/08).
3. Progress Report
The research project is in its inaugural year (commenced November 2008). Two forced-convection temperature control and data acquisition systems were renovated and upgraded for new research during summer 2009. Deployment of the systems in the field is concurrent with submission of this report. The temperature of fruit clusters on mature grapevines is being controlled under natural conditions in the vineyard from June through October 2009. Experimental data are being recorded continuously. A database of low temperature exotherms, indicators of cold hardiness in plants, was completed during winter 2008-2009 for dormant grapevine buds and canes from multiple cultivars. Own-rooted V. vinifera cv. Malbec and cv. Syrah grapevines were cordon-trained to a single-curtain trellis with vertical shoot positioning (VSP) and spur-pruned. Plots were maintained weed free and irrigated with an amount of water estimated to meet or exceed crop evapotranspiration (ETc). Research plots in a commercial vineyard of Merlot were differentially irrigated and half of the vines in each plot were sprayed with a clay particle film. Vine physiological response and fruit maturity at harvest was evaluated. Cultivars in an experimental vineyard were differentially irrigated. Diurnal leaf gas exchange and leaf water potential were measured on four cultivars under well-watered and water deficient conditions on two dates. Fruit was sampled before and after veraison and yield and berry composition were evaluated at harvest. Selection and evaluation of analytical methods for identification and quantification of food quality components (phenolics, free amino acids, ammonia, sugars, organic acids, etc) were conducted this past year.
1. Dynamic Crop Monitoring and Yield Estimation. Transient and long-term labor shortages in U.S. agriculture require innovative, automated approaches to production practices that long have been manually accomplished in specialty crops. Work conducted by ARS scientists in Corvallis, OR addressed the juice grape industry's need for an automated alternative to the labor-intensive practice of estimating yield from grape samples collected by hand. The Trellis Tension Monitor (TTM) that was developed over several years for tracking crop growth and estimating yield in trellised crops, specifically grapevines, was shown in FY09 to outperform the commercial yield estimation technique used by major juice processors. The TTM technology can be applied by juice processors or wineries as a stand-alone, remote yield estimation technique and as a decision aide to confirm desired levels of fruit thinning or to target the timing of hand sampling for supplemental, traditional yield estimation approaches.
2. Brief Exposure to Temperature Extremes Compromises Grape Quality. There is a need to understand the effect of temperature on natural chemical compounds in the skins of the grapes that impinge directly on quality and thus the market price of the grapes and their finished products. Specifically, the compounds that were analyzed impart color and other desired attributes to the fruit that may have beneficial health effects in humans. ARS scientists in Corvallis, OR used a model red grape variety of major economic importance to U.S. growers and processors to study the deleterious effects of extreme high fruit temperatures on two classes of antioxidant compounds in grapes. Knowledge of natural temperature fluctuations in vineyards and their effects on grape quality led to practical recommendations for growers to adjust vineyard management practices in warm grape-growing regions to maintain an environment conducive to the highest quality fruit.
3. Wine grape response to foliar particle film under differing levels of water stress. Wine grapes are grown in arid climates with less water than is needed for optimal growth in an effort to produce higher quality grapes for wine production. However, water deficiency reduces canopy size and increases the risk of fruit exposure to potentially damaging solar radiation. Foliar particle film was applied to grape vines by ARS scientists to determine whether it could increase vine water use efficiency and reduce the incidence of surface browning on exposed clusters. The particle film did not prevent surface browning of western exposed clusters but increased net diurnal leaf gas exchange and may increase vine-carrying capacity. Particle film increased the strength of correlations between maturity and yield attributes, suggesting a potential benefit for increasing uniformity of berry quality within a harvest. Results from this study provide wine grape growers in arid regions having high solar radiation with information that they can use to determine the economic benefit of using particle film for meeting their production and quality goals.
4. Evaluation of approaches for food quality component analysis. A thorough identification of food quality components is important to discern how cultivars, environment, post-harvest conditions, processing methods, etc. ultimately influence food. Chicoric acid is a compound found in Echinacea purpurea extracts and is sold in capsules as a dietary supplementation in the United States. ARS scientists in Corvallis, OR were the first to identify and quantify the presence of chicoric acid in basil leaves, a widely used culinary herb. Basil is a more available and less expensive source for chicoric acid than E. purpurea and results of this research could increase the market for basil.
Tarara, J.M., Blom, P.E., Shafii, B., Price, W.J., Olmstead, M.A. 2009. Modeling seasonal dynamics of canopy and fruit growth in grapevine for application in trellis tension monitoring. HortScience. 44(2):334-340.