Effects of elevated CO2 on grapevine (Vitis vinifera L.): Physiological and yield attributes
During the 2004, 2005 and 2006 growing seasons, physiological and anatomical leaf characteristics and productivity were studied in field-grown grapevines (Vitis vinifera L.) cv. 'Touriga Franca' under ambient (C, 365 Â¬Â± 10 ppm) or elevated carbon dioxide [CO2] (E, 500 Â¬Â± 16 ppm) under Open-top chambers (OTC-C and OTC-E, respectively). The elevated [CO2] concentra- tion increased net photosynthetic rate (A), intrinsic wa- ter use efficiency (A/gs), leaf thickness, Mg concentra- tion, C/N, K/N and Mg/N ratios and decreased stomatal density and N concentration. Nevertheless, stomatal conductance (gs), transpiration rate (E), photochemi- cal efficiency (Fv/Fm), leaf water potential, SPAD-values and Red/Far-red ratio transmitted by leaves were not significantly affected by [CO2]. Meanwhile, there is no evidence for downward acclimation of photosynthesis and stomatal conductance. Yield, cluster weight and vigour showed an increase in elevated [CO2] treatment but yield to pruning mass ratio was unaffected. Despite elevated [CO2] stimulates grapevine photosynthesis and yield, more long-term studies, particularly at sub-opti- mal nutrient and water availability, are needed in order to reveal the grapevine responses to climate change in the Mediterranean area.