Effects of drought on light-energy dissipation mechanisms in high-light-acclimated, field-grown grapevines.

The response of several light-energy dissipation mechanisms to water shortage was analysed in a 10-year study in field-grown, high-light-acclimated grapevines, and compared with those of greenhouse-grown, low-light-acclimated grapevines. Dissipation mechanisms, except leaf photochemistry, differ among cultivars and acclimate to the prevailing light conditions during growth. However, no additional acclimation to drought was observed.

Effects of drought on photosynthesis in grapevines under field conditions: an evaluation of stomatal and mesophyll limitations.

The effect of diffusional and photochemical limitations to photosynthesis was assessed in field-grown water-stressed grapevines (Vitis vinifera L.) by combined measurements of gas exchange and chlorophyll fluorescence. Drought was slowly induced, and the progressive decline of photosynthesis was examined in different grapevine cultivars along a continuous gradient of maximum mid-morning values of stomatal conductance (g), which were used as an integrative indicator of the water-stress conditions endured by the leaves.