Sponsor Agencies: WSU Ag Research Center – Emerging Research Issues Grant Program; Wine Advisory Committee – WA State Grape and Wine Research Program; and Northwest Center for Small Fruit Research
Jacoby, P.W.*; Peters, R.T.; Sankaran, S.; and Khot, L.R.
Three separate projects were funded to determine potential abilities of grapevine root systems to maintain or increase water use efficiency by delivering water at various depths (1-4 feet) in the soil. Rather than using buried lines with drip emitters in contact with soil and subject to damage by burrowing rodents, covered drip emitters were placed on top of vertically inserted delivery tubes into which water was supplied from above-ground standard drip hose via micro-tubing. Vine root growth responses are quantified from digital photography from a camera inserted through a clear polyvinyl tube (mini-rhizotron) at two week intervals throughout the growing season. Physiological plant responses to treatment effect are estimated by measurements of mid-day xylem pressure potential and infrared determination of CO2 use as a measure of photosynthesis. These measures are compared with color enhanced spectral imagery from aerial and ground based cameral systems for early detection of plant water stress under various irrigation regimes.