2013 Annual Report
1a.Objectives (from AD-416):
1. Develop sustainable water management strategies for wine, table, raisin, and juice grape production using limited water supplies.
2. Develop sustainable water and soil management strategies for minimizing the impacts of drought and salinity on the root zone environment, grape yield and quality.
3. Establish rootstock recommendations based on drought resistance and salinity tolerance.
4. Quantify the effects of various water management strategies on fruit and product composition, and sensory qualities.
5. Quantify the economic impacts of drought and salinity on grape production under different biophysical soil and water characteristics and alternative management strategies.
6. Disseminate study findings via web based education and farmer outreach.
1b.Approach (from AD-416):
This research will be conducted using both laboratory and field research sites. The field research will conducted in the Central Valley and Paso Robles, CA and in Washington State. Laboratory studies will be conducted at UC Davis and the Salinity Laboratory in Riverside, CA, as well as a Washington State University in Pullman, Washington. Specialty Crops Research Initiative.
This project supports research under objective 2 of the in-house project, developing sustainable water management strategies. Nutrition and irrigation are critical components of sustainable management. This research quantifies the nitrogen requirements for pomegranate.This multi-state and multi-institute research project is evaluating sustainable water management practices for table, wine, raisin, and juice grapes being grown in California and Washington State. The water management strategies are evaluating the effect of deficit irrigation on fruit and wine quality as well as yield (Deliverable 1). The economic impact of the proposed management strategies is being evaluated by a resource economist at the University of California Riverside (Deliverable 5). The impact of irrigation with poor water quality on soil salinity is being evaluated by ARS scientists at the George E. Brown Jr. Salinity Laboratory (Deliverable 2). Rootstocks are being evaluated for both salt and drought tolerance by ARS and UC Davis scientists (Deliverable 3). This is the third year of operation of the study and good progress is being made on each of the objectives. The details of the research by scientists from UC Davis and Washington State University are given in project reports for the individual projects covering the economics (5302-13000-011-10A), technology transfer (5302-13000-011-09 A), rootstocks (5302-13000-011-11A) and water management strategies for juice and wine grapes (5302-13000-011-08A).
(Deliverable 1 – California) Field trials were established on four locations in California to quantify the impact of deficit irrigation on early and late season table grapes, raisin grapes, and wine grapes. There are a total of 3 irrigation treatments with 4 replications on each trial in California. The irrigation treatments were based on grape physiology and grower practice. There have been significant reductions in applied irrigation water in the third irrigation treatment during each season on the early season table grapes. The third treatment resulted in lower yields and poorer quality grapes in the early season table grapes in the second year harvest, with the opposite result in the second full year of the trial. The quality data from the first year didn’t demonstrate any significant difference as a result of the irrigation treatments. A capacitance probe system for measuring soil water remotely was installed in each treatment of the California trials. This system measures the change in soil water content and sends the data over a wireless network. These data can be accessed in real time to monitor the crop water use and irrigation. The system has operated very well over the past year and has provided excellent data in support of the project. The data from the first year wine studies have not demonstrated any significant quality differences related to irrigation management. Field trials in Washington State studies continue in both the Concord and Cabernet Sauvignon plots. Water balance studies confirmed the need for a new soil water monitoring strategy to capture soil water dynamics between the irrigation intervals.
Progress has been made on developing the surface renewal system into a stand-alone device that will provide growers real time estimates of crop water use at a commercially viable price. The conceptual details have been completed and work is progressing on finding suitable instrumentation to achieve an appropriate price point.
2)Salinity field studies have quantified differences in salinity management due to irrigation practices in the Coachella Valley of California that required application of chemicals to halt plant growth to initiate dormancy. Salinity studies on the California coast are difficult because of the impact of rainfall on leaching soils and there is very little accumulation of salt. Progress is being made on the characterizations and management strategies.
3)Rootstock studies have resulted in a hydraulic screening process that evaluates root hydraulic conductivity. It was determined that drought significantly reduced root hydraulic conductivity and the responses varied between genotype. However, while this procedure is useful, it is technically challenging and not suitable for use in doing a large number of screens. Instead research is focused on the chemical and structural changes in fine roots that contribute to the loss in hydraulic conductivity. We theorize that the formation of suberized cells in response to drought is responsible for the loss of conductivity. Research is being focused on characterizing the suberin development in roots as an indicator of drought stress for use in screening. Work is continuing on the effect of drought on the formation of embolisms in the vascular system of grape roots and the repair. A major effort is being undertaken to understand the patterns of water absorption in grape roots. It is not known where water is absorbed in grapevines because of the woody nature of the root system. If water is absorbed primarily by the root tips then current procedures for evaluating crop uptake from an extensive woody root system may not be appropriate. The data set has been completed for the root architecture characterizations of all widely available rootstocks in California. These were obtained using 4 weeks of growth in rhizotron containers which were determined to provide the highest quality data. A series of field and laboratory studies were used to evaluate the effect of drought on 7 commercial rootstocks. Well watered and water stressed regimes were used on the rootstocks in the second year. It was determined that drought had little or no effect on root architecture. The persistence of this trait support research to evaluate this trait in a greenhouse where more stocks can be rapidly evaluated.
4)This deliverable was established to insure uniformity across states with regard to analysis of fruit and wine quality. E.J. Gallo has provided wine making and analysis, so the quality parameters are consistent.
5)Excellent progress has been made on developing the inter-seasonal economic model to characterize the effect of water management on grape yield. Two main tasks were accomplished this year. A field-level, bio-economic model was developed that is capable of describing the inter-seasonal dynamics of water applications to perennial crops. The model incorporates the effects of crop age, soil salinity, and irrigation history on yield potential by using an unobserved biomass state variable. The biomass variable, which represents vine capacity, captures the irrigation history of the crop in a single state variable, thus allowing the use a stochastic dynamic programming framework to analyze optimal management decisions over the life of the crop given stochastic water supplies. Yields are a function of plant age, biomass, current season water applications and salinity. We learned how to use Hydrus-1D and adapt it to our applications so as to generate more accurate crop-water-salinity production functions that will be used to replace the generic functions we have used to date to develop and update our intra- and inter-seasonal dynamic grape production model. We also refined our crop-water-salinity production functions to better represent how changes in water application influence within season growth and carryover growth of vine capacity into the next season.
6)Technology transfer was accomplished through presentations at professional meetings and conferences. A website developed for the project is currently being hosted by the National Grape and Wine Initiative and is being populated with research results.