![]() Facing the new challenges imposed by global warming those regulations are being, or have already been relaxed in some designations of origin in several countries including Spain and Italy, allowing winegrowers the opportunity to irrigate. The rationale behind these regulations has however been questioned from a scientific perspective because it remains unclear whether excess soil water supplied during ripening leads to an increase in berry size and thereby alter wine composition ( Keller et al., 2016 Keller and Shrestha, 2014). Historically, these rules have been imposed for the sake of wine quality because water supply during late ripening is ostensibly implicated in an increase in berry weight and yield, with a consequent dilution of quality determining compounds. Traditionally, in many protected wine-producing areas, so called designations of origin, for example the French AOP system, irrigation is restricted to the period from flowering to the 15 th of August, which corresponds roughly with the date of véraison. ![]() The latter represent a particularly challenging new commitment for most growers of regions, where vine cultivation has historically been rainfed and vine water status monitoring and management was not necessary. Those consist of different agronomic practices such as adaption of planting density, training system, leaf area, the choice of cultivar and rootstock ( Ollat et al., 2016 Romero et al., 2018) and eventually the installation of irrigation systems. For winegrowers, different drought mitigation strategies exists as reviewed by Medrano et al. Global warming leads to altered precipitation patterns and to an increasingly negative climatic water balance during the vegetative cycle ( Schultz and Stoll, 2010 van Leeuwen and Destrac-Irvine, 2017) which increases the risks of drought periods. This is particularly true regarding viticulture where a tradeoff between yield loss and quality gain can be economically very significant for producers, and highly modulated by water supply. In a world where fresh water is becoming an increasingly scarce resource with 80% of it used for irrigation of agricultural crops ( FAO, 2016 ), the optimization of water use should be a primary objective for agriculture. Recent technical and scientific advances shed new light on how site specific irrigation strategies matching production objectives could improve vineyard water use. ![]() Practical consequences regarding the effects of vine water regime on vine water regulatory mechanisms are discussed. Latest literature on irrigation frequency, water stress memory and the impact of abiotic factors such as VPD (Vapor Pressure Deficit), radiation, temperature and canopy architecture on vine physiology and water use, raise important questions on water status assessment and the implementation of irrigation strategies. ![]() This review summarizes the most recent studies on the impact of water deficit stress on vine and berry physiology it discusses the latest scientific advances regarding hormonal and hydraulic regulation and segmentation and addresses the current debate on iso/an-isohydricity within vine cultivars. The increasing risk of water deficit stress due to global warming subjects winegrowers of traditional rain fed viticulture regions to new challenges regarding vine water status assessment and possible drought mitigation strategies, such as irrigation.
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