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 +/- 10 ppm) or elevated carbon dioxide vertical bar CO2 vertical bar, (E, 500 +/- 16 ppm) under Open-top chambers (OTC-C and OTC-E, respectively). The elevated vertical bar CO2 vertical bar concentration increased net photosynthetic rate (A), intrinsic water use efficiency (A/g(s)), leaf thickness, Mg concentration, C/N, K/N and Mg/N ratios and decreased stomatal density and N concentration. Nevertheless, stomatal conductance (g(s)), transpiration rate (E), photochemical efficiency (F-v/F-m), leaf water potential, SPAD-values and Red/Far-red ratio transmitted by leaves were not significantly affected by vertical bar CO2 vertical bar. Meanwhile, there is no evidence for downward acclimation of photosynthesis and stomatal conductance. Yield, cluster weight and vigour showed an increase in elevated vertical bar CO2 vertical bar treatment but yield to pruning mass ratio was unaffected. Despite elevated vertical bar CO2 vertical bar stimulates grapevine photosynthesis and yield, more long-term studies, particularly at sub-optimal nutrient and water availability, are needed in order to reveal the grapevine responses to climate change in the Mediterranean area.