Improving Water Saving Techniques and Fruit Quality in Oregon Vineyards

• 2016 annual report

Commodities

• Fruits: grapes

Practices

• Crop Production: irrigation, application rate management
• Education and Training: demonstration, farmer to farmer, on-farm/ranch research

2014 and 2015 were the two hottest years on record in Oregon. Reservoirs are now at historic lows, and as we enter the 2016 growing season water shortages threaten many agricultural sectors including Oregon vineyards that rely on irrigation learning to use water more efficiently is essential. We believe on-site research is one of the best tools vineyard managers have to learn and adapt to our changing environment. Our objective is to develop clear protocols based on vine-stress measurements that can significantly reduce water consumption in Oregon vineyards while simultaneously improving grape quality. Over the past two seasons we have used a portable leaf porometer in several vineyards and have consistently seen that irrigation programs in most vineyards apply excessive amounts of water. We believe that we can significantly reduce water use in irrigated sites participating in the on-farm research funded by this grant, and that these results can further influence irrigation practices in vineyards throughout Oregon, resulting in substantial water savings. Our plan is to conduct research on four irrigated Pinot Noir vineyards located in arid growing regions (three in the Rogue Valley AVA and one in the Columbia River Gorge AVA), as well as one non-irrigated vineyard located in the Chehalem Mountains AVA near Portland. All locations have vineyard blocks planted to Pinot Noir clone 777, which will act as our designated trial clone; eliminating variability between different grape cultivars and clones. Irrigated vineyards will be subjected to two treatments with two replicates. The first treatment will be irrigated based on a regulated deficit irrigation (RDI) schedule that uses ET to restrict vine growth by applying water at a deficit rate. RDI programs are commonly used in irrigated vineyard operations, and will act as the control/industry standard. Due to differences in site microclimates and soil characteristics the amount of water applied per irrigation set may be different for each site, but the practice and calculations will be kept consistent across all four sites. A portable leaf porometer will be used to determine timing of irrigation sets for the second treatment, porometer regulated deficit irrigation (PRID). The Decagon SC-1 portable leaf porometer measures stomatal conductance (units = mmol/m/s2) which is regulated by the vine’s stomata in response to temperature, relative humidity, photosynthesis, and vine water status. When the vine has access to sufficient water resources the stomata are open and the porometer will record high conductance (>300mmol/m/s2); this will indicate that no water is necessary at that time. Once the stomatal conductance readings start to fall below 250 mmol/m/s2, specifically during the period between fruit set and veraison, we will have reached our targeted water “stress” level, and irrigation will commence. The PRDI treatment will be irrigated to maintain a mild stress (150-200mmol/m/s2) until veraison. During this period of regulated stress we expect to induce positive changes in berry development that translate into increased fruit quality by harvest. This treatment is designed to acknowledge the vine’s physiological demand for water throughout the season, and provide us with the opportunity to save water over several weeks of induced stress. Each treatment will have a total of 20 reference vines (10 vines/replicate) designated for data collection which will include: porometer readings, shoot lengths, pruning weights, vine fruitfulness counts, harvest cluster weights and fruit analysis. Outreach will be facilitated by all participating growers. All participants have connections to viticulture technical groups, both in the Northern Willamette Valley and Southern Oregon; these groups will be a great way to bring the research and findings directly to local growers. The technical group in the Northern Willamette led by Dr. Patty Skinkis (OSU) draws 15-30 growers each meeting to discuss current research, viticulture practices relevant to the specific time in the season, new/old/or interesting vineyard ailments observed. The technical group in southern Oregon, led by top producers in the region involved in the Rogue Valley Winegrowers Association, gather to discuss topics of interest in the region and ways to bring continued educations and workshops to growers throughout the region. These direct connections with the industry will provide a significant number of opportunities to bring our research and outreach programs to the attention of local growers. With the drought currently present in Oregon, Washington, and California predicted to worsen many farmers will continue to experience the negative effects these conditions have on yields and quality. In order to remain economically sustainable we must adapt our agricultural practices – this trial is how we stay ahead of the drought and learn to adapt.

• Educate participating and regional growers about the trial, techniques used to conduct on-site research, and the support of the Western SARE program.
• Decrease total irrigation water used during the growing season
• Increase fruit quality (i.e. increase total anthocyanins, increase skin to pulp ratio of berries) of Pinot Noir clone 777 grapes.
• Monitor the stomatal conductance of both conventionally deficit irrigated (RDI), targeted deficit irrigated (PRDI), and non-irrigated grapevines to better understand water use trends of Pinot Noir (clone 777) on different soil types, and in different climates.
• Quantify differences in specific fruit quality parameters between treatments and sites.
• Measure changes in irrigation practices over the course of the trial, and (where possible) determine how much the trial and outreach has influenced these changes.