Physiological and biochemical responses of Semillon and Muscat Blanc à Petits Grains winegrapes grown under Mediterranean climate

• Muscat variety presents superior physiological and biochemical responses to Douro region.
• Afternoon measurements better discriminate the functional grapevine performance.
• An increased Ca2+ and Mg2+ concentrations is associated with higher water use efficiency.
• Leaf oxidative damage affects photosynthesis and yield.

Climate variability exerts a profound influence on grapevine leaves and production. Leaf water potential, stomatal conductance, CO2 assimilation rate, transpiration rate, intrinsic water use efficiency, lipid peroxidation and leaf biochemical composition and yield were determined in two Vitis vinifera varieties: Muscat Blanc à Petits Grains and Semillon, cropped under similar pedo-climatic conditions, in 2011 and 2012 growing seasons. Muscat Blanc à Petits Grains vines presented higher CO2 assimilation rate and photosynthetic pigments concentration as well as higher midday leaf water potential when compared with Semillon in both years. In agreement with that statement, Muscat Blanc à Petits Grains had higher soluble sugar and lower total phenol concentrations. Additionally, Semillon yielded more in 2011 but presented lower yield in 2012, a drier year. In conclusion, the Muscat Blanc à Petits Grains seems to be better adapted to more stressful climatic conditions such as of the Douro Demarcated Region, Portugal.