Funding Agency: WA State Concord Grape Research Committee
WSU Investigators: Pete W. Jacoby, Sindhuja Sankaran, Lav Khot, Markus Keller, and Troy Peters
A Concord grape vineyard has demonstrated the potential to remain productive during extended periods of drought through the use of subsurface irrigation with considerable savings in water compared to surface drip irrigation. During the first two years of this project, plant water stress, as determined by mid-day measurement of stem water potential, was substantially less in plots receiving subsurface irrigation at the 2- and 3- depths than in surface and 1-foot depths. However, by end of 2016, grape clusters were consistently heavier with increase depth of irrigation delivery, with lightest clusters from the surface drip irrigation treatment and the heaviest from the 4 foot depth. This finding suggests that vines were able to develop deeper roots capable of extracting moisture from the full range of the soil profile. During 2017, growing conditions that resulted from above average precipitation and cooler temperatures compromised the various irrigation treatments and data was not taken at time of harvest. This study will continue if funding is provided to allow data collection during the 2018 growing season.