Abstract:
In the Mediterranean area, changes in crop production and quality are expected in the future, due to one or more stress factors associated with climate change. Among them, plant responses to atmospheric CO2 concentration increases, enhanced temperatures and scarce water availability are a matter that deserves further investigation. In this study, the effects of the three above-mentioned factors, acting individually and/or in interaction, on grapevine reproductive growth and berry quality were investigated in three consecutive growing seasons (2013, 2014, and 2015) in the cultivars red and white Tempranillo. Eight different treatments were applied from fruit set to maturity (2 CO2 levels (400 versus 700 mu mol mol(-1)) x 2 temperature treatments (ambient versus ambient +4 degrees C) x 2 water availability regimes (well irrigated versus cyclic drought)) in four temperature gradient greenhouses located at the University of Navarra (Pamplona, Spain). Yield was significantly reduced by drought and was year-dependent. Eventual heat shocks (above 35 degrees C) in the first week of July in 2015 induced berry burn, browning and loss of 50% of the berries. Regarding quality, simulated climate change scenarios affected to greater extent technological (primary metabolism) than phenolic (secondary metabolism) maturity. Indeed, high temperature and drought significantly and consistently increased must pH, due to decreases in malic acid. On the contrary, elevated CO2 decreased pH associated with significant increases in tartaric acid. Differences in the response of red and white Tempranillo were found. Acidity was lower (and pH higher) in white than in red Tempranillo, due to lower malic and tartaric acid concentrations. Also, total polyphenol index was lower in the white variety, in part due to the absence of anthocyanins. Fresh bunch weight and berry water content were higher in the white than in the red variety. Interactions found among variety, year, water availability, temperature and CO2 have been highlighted and discussed. (C) 2017 Elsevier B.V. All rights reserved.