Training a grapevine involves a manipulation of vine form. The type of training may lead to differences in total leaf area and the percentage of leaf area well-exposed to light. Consequently, the ability for a grapevine to photosynthesize efficiently depends upon its training system and the accompanying light microclimate of its leaves. In addition to altering the light microclimate of the canopy, training may impact numerous other variables such as fruit bud differentiation, cluster exposure, vine water status, and leaf transpiration. Modification of vine training systems to achieve balance between vine vigor and yield has led to divided canopy systems that might simultaneously increase yield and improve fruit composition through optimization of canopy light microclimate. Consequently, many training systems have been identified as being capable of improving wine quality through a combination of enhanced canopy and fruit microclimate.