Effects of root-zone micro-irrigation on Cabernet Sauvignon

During 2015, vines receiving season-long drip irrigation delivered into the lower root zone via hard plastic tubes yielded 70 % of commercial production while receiving only 15% of the water as the vines receiving full commercial rates of surface drip irrigation. Vines receiving direct root-zone (DRZ) irrigation at rates reduced to 60, 30, and 15% of commercial drip irrigation (DI) produced individual clusters with higher numbers of berries, yet smaller in size, than did clusters from vines receiving full rates of surface drip irrigation. Preliminary findings suggest that a new form of subsurface micro-irrigation may have potential to not only conserve more water than surface drip irrigation, but may produce grapes of a higher and more desirable quality for producing premium red wines. Relative water use efficiency during 2016 was 1.5, 2.5, and 5.0 times greater for grapes produced by sub-surface irrigation at rates of 60, 30, and 15%, respectively, than for surface drip irrigation. Interrupted irrigation delivery did not provide any advantage over uninterrupted delivery. Treatments were repeated during 2016 and fruit quality at harvest was analyzed for several key factors attributed to high quality wine grapes.