EFFECT OF DIFFERENT IRRIGATION STRATEGIES ON VINE PHYSIOLOGY, YIELD, GRAPE COMPOSITION AND SENSORY PROFILES OF VITIS VINIFERA L. CABERNET-SAUVIGNON IN A COOL CLIMATE AREA

Aim: The efficacy of partial root zone drying (PRD) and regulated deficit irrigation (RDI) on vine physiology, yield components, fruit composition and wine sensory profiles of 'Cabernet-Sauvignon' was investigated in a cool climate region in Ontario, Canada. Methods and results: Field experiments were conducted in a Cabernet-Sauvignon block in Niagara-on-the-Lake, ON Canada between 2006 and 2008. There were five treatments : non-irrigated control, PRD, full irrigation [100 % of crop evapotranspiration (ETA and two levels of RDI (50 and 25 % ET,). Treatments started immediately after fruit set and continued until post-veraison. Soil and vine water status were apparently controlled not only by the amount of water but also by the irrigation strategy used. In the PRD treatments, soil moisture, leaf water potential, and transpiration rate were generally lower than in 100 % ET, but higher than non-irrigated and RDI treatments. Almost all treatments were different than in non-irrigated vines in fruit composition and wine sensory attributes. Wine sensory attributes differed considerably due to the amount of irrigation water applied in 2007. RDI strategies were more consistent than the PRO treatments in their effect on vine water status, grape composition and wine sensory profiles. Inconsistent patterns across seasons for some variables indicated that besides soil and vine water status, there were other factors that impacted vine physiology, yield components and berry composition. Conclusions: ROT treatments improved wine quality when compared with full or either non-irrigated treatments. Overall, use of ROT irrigation or PRO during dry and warm years can improve grape composition in cool climates. Significance and impact of the study: To the best of our knowledge, this is the first evaluation of PRO and ROT on Cabernet-Sauvignon in a cool humid climate. It suggests that although RDI strategies are more effective, PRO also has value, particularly in dry seasons.