Optimizing Irrigation for Mechanized Concord Juice Grape Production

Background and goals Economic considerations water shortages associated with climate change are driving the conversion of many hand-pruned furrow- or sprinkler-irrigated juice grape vineyards in arid eastern Washington to mechanical pruning drip irrigation. However, producers have traditionally avoided plant deficits, fearing a decline vineyard productivity. Methods key findings We conducted six-year field trial test impact eight drip-irrigation treatments on large, mechanically-pruned Concord grapevines. found an estimated crop coefficient 1.05 between fruit set harvest. Replacing 75% evapotranspiration (ETc) from through harvest reduced annual irrigation supply by 20% below that 100% ETc control without altering canopy size, yield, composition. Decreasing 50% at veraison saved only 8% water, while irrigating veraison, thereafter, use 30% but decreased size yield 14%. 150% increased seasonal did not alter Conclusions significance Deficit does composition, so long as vines experience mild stress (midday stem potential > −1 MPa) before veraison. Irrigating impose preveraison moderate postveraison optimally balances goals conservation quality sustainability production.