2012 Annual Report
1a.Objectives (from AD-416):
Assess and extend practical short/near term solutions for decreased water quantity and quality (i.e. soil salinity) issues important to grape growing regions of the Western United States.
1b.Approach (from AD-416):
Assessment of the effect of recommended water and salinity management strategies on quality, sensory, and yield parameters for table, raisin, juice and wine grapes and their commercial products. Development and expansion of commercially available grapevine rootstocks that better resist drought and tolerate salinity.
Quantification of the economic sustainability of implementing the strategies in viticulture. Outreach, extension and educational training to disseminate recommendations to grower and academic audiences via presentations, publications, Web-based learning and tailgate outreach. Documents Reimbursable with NIFA.
This agreement was established in support of objective 3 of the in-house project, which is to develop sustainable water management practices for vineyards". As part of this larger project, we have the responsibility of addressing the following two specific project objectives:.
1)Develop technologies to quantify real-time remotely accessible measurements of vineyard-scale evapotranspiration and vine water use; and.
2)Development and expansion of commercially available grapevine rootstocks that better resist drought and tolerate salinity.
Objective 1: Surface renewal (SR) is one technique with potential to meet this need, but it must first be appropriately adapted for use in viticultural management. SR instrumentation is inexpensive and the technique is theoretically simple, but current SR systems require complicated calibration techniques and data-crunching capabilities. The project aims to develop an adaptation of current SR techniques suitable for monitoring water use in vineyards through a more user-friendly data interface accessible from a Web access device. This research is being conducted at University of California, Davis. We recently published two invited manuscripts in a special issue of Boundary Layer Meteorology (Shapland et al. 2012a &2012b). Two additional manuscripts are nearing completion and will be submitted to the journals by October 2012.
Over the past few months, we made excellent progress in calibrating SR for the use of more sturdy (thicker gauge) thermocouples under field conditions. The fine gauge thermocouples, originally used in for SR, are highly responsive and work well for tracking the air temperature fluctuations at high frequency, however, they are fragile and required much maintenance. We successfully calibrated fine gauge thermocouples against heavier gauge (more sturdy) ones. The surface renewal sensible heat flux estimates from the heavier thermocouples (76 micron diameter wire) are strongly correlated with those of the 13 micron diameter (fine gauge) thermocouples. We established SR fields stations at two weighing lysimeter sites (Wheat in Davis and Thompson Seedless grapevines in Parlier) to compare results against the water loss estimates from the weighing lysimeters
Based on our progress, we have recently been accepted to participate in the Green Technology Entrepreneurship Academy (GTEA) at University of California Davis, in late June 2012- GTEA brings scientists together with technology investors to help bring products to market. Our ultimate goal is to develop SR as a stand-alone user friendly technology for growers across all agricultural sectors. To improve irrigation efficiency, our technology will report daily water use of a crop field to a farmer’s mobile device.
Objective 2: In coordination with efforts from researchers at University of California, Davis, we developed a screening technique to evaluate the hydraulic conductivity (in this case the leakiness) of fine roots of grapevines. We utilized a variety of rootstocks to perform this analysis and found that fine root hydraulic conductivity was significantly reduced by drought and salinity treatments, and responses varied among rootstock genotypes tested. We have initiated additional follow-up experiments to expand this work to additional rootstocks. We also evaluated the effects of gypsum on the physiological growth parameters of grapevine roots and these results suggest that gypsum can ameliorate the negative effects of salt on grapevine root growth (a pattern that was consistent across rootstock genotypes) in some way other than “washing” the sodium chloride ions from the soil. Finally, we have initiated efforts to use high resolution computed tomography to assess the contribution of xylem vasculature to grapevine rootstock drought resistance/tolerance. This work involves both woody roots from 10 rootstocks (commercially available and new accessions from desert SW USA) and live plants- which are being used to evaluate the ability of the vines to repair drought induced embolism once it has formed.