Carbon balance, partitioning and photosynthetic acclimation in fruiting gravepine (Vitis Vinifera L. CV. Tempranillo) grown under simulated climate change (elevated CO2, elevated temperature and mode rate drought) scenarios in temperature gradient greenhouses

Abstract

Experiments were conducted in grapevine (Vitis vinifera L. cv. Tempranillo) fruit-bearing cuttings, using temperature gradient greenhouses (TGG), to investigate the possible effects of future climate scenarios: elevated CO2 (700 ppm) vs. ambient (ca.375 ppm), elevated temperature (+4ºC) vs. ambient and partia l vs. full irrigation, on C balance, partitioning and grape quality. Carbon balance was followed monitoring net photosynthesis (AN, C gain), respiration (RD) and photorespiration (RL) (C losses). For C partitioning characterization, 13 C isotopic composition (δ13C) was modified (-24.93 ‰) in the elevated CO2 TGGs, with respect to that of the ambient TGGs (-10.30 ‰). Elevated CO2 increased transiently (after 10 days of treatment) AN irrespective of water availability and temperature, but effects disappeared 10 days later. In most cases, no differences in RL were found. When grown under ambient temperature (regardless of water status), leaves respired more under elevated than under current CO2 concentrations at both sampling dates, whereas all leaves respired similarly to controls when grown under elevated temperature. Carbon and N isotopic composition (δ13C and δ15N respectively) was characterized in roots, cuttings, shoots, petioles, leaves, rachides and berries. Data revealed a low C-sink strength of cuttings and rachides, whereas leaf N decreased as a response to elevated CO2 . Plants exposed to elevated CO2 did acclimate. Such acclimation was reflected in lower AN rates measured at elevated CO2 and a higher C/N ratio in plants grown at elevated CO2. After 20 days of treatment, no oxidative damage to chlorophylls or carotenoids was observed, suggesting a protective role of CO2 either at current or elevated temperatures against the adverse effect of water stress. Treatments simulating climate change influenced g rapevine maturation. Climate change (elevated CO2 in interaction with water deficit, but irrespective of temperature) shortened maturation time. pH and extractable anthocyanins were not affected, whereas acidity, malic acid, total and potential anthocyanins, phenolic richness, colour intensity and tonality index were only slightly altered under some particular circumstances.