TY - JOUR T1 - Irrigation Strategies Impact Baco noir Grapevines in Ontario. I. Vine Physiology, Vine Size, and Yield Components JF - American Journal of Enology and Viticulture JO - Am J Enol Vitic. DO - 10.5344/ajev.2017.16093 SP - ajev.2017.16093 AU - Gabriel Balint AU - Andrew G. Reynolds Y1 - 2017/03/23 UR - http://www.ajevonline.org/content/early/2017/03/15/ajev.2017.16093.abstract N2 - Irrigation experiments were conducted on French-American hybrid Baco noir in a vineyard in Virgil, Ontario, Canada, in 2005–2007. Effects on vine physiology, shoot growth, and yield components of three regulated deficit irrigation (RDI) levels [100%, 50%, 25% crop evapotranspiration (ETc)] combined in a factorial experiment with three timings of irrigation initiation [fruit set (FS), lag phase (LP), veraison (VRN)] were studied vs. a non-irrigated control. The control and late deficits were frequently below wilting point in all seasons, and soil water content exhibited substantial variation between treatments up to the 50 cm depth. Transpiration (E) rates were highest in July and August and dropped by late August. Over the growing season, the control had the lowest E rate while the 100% ETc initiated at FS was highest. In 2005 and 2007, shoot growth rate had almost the same trend; 25% ETc was slightly greater than the control. The 100% ETc imposed at FS had the highest growth rate. Leaf water potential (ψ) was higher (less negative) in 100% and 50% ETc compared to the control throughout the growing seasons. Leaf ψ displayed a downward trend at the end of August in all treatments and experimental years. The control had the lowest (most negative) leaf ψ value in 2007. The control and 100% ETc initiated at FS did not show differences in all yield components. Trends in yield were not constant across treatments, although RDI treatments showed an increase in some yield components compared to the control. The RDI technique could be a profitable management tool in Ontario vineyards, with positive effects on vine physiology and yield. ER -