Photosynthetic activity in grafted and ownrooted grapevine cv Erbaluce trained to four trellis systems.

Photosynthetic activity of grafted (Kober 5BB) and ownrooted grapevines (cv. Erbaluce) trained to four trellis systems (alternate curtain, central curtain with one or two canes and pergola) was assessed for three years. The overall photosynthetic response to training, the seasonal and diurnal photosynthetic trends and the response of the training systems to different photosynthetic photon flux densities were evaluated. The training systems had a significant influence on the rate of photosynthetic assimilation: the two central curtains generally had higher rates of CO2 uptake compared to the vines which were trained to pergola and to alternate curtain. With one exception Kober 5BB improved net assimilation rates.