The influence of grapevine rootstocks on scion growth and drought resistance

Grapes are a widely cultivated and economically important crop. Climate change is increasing the focus and investment on the development of more drought resistant varieties. However, markets often dictate specific grape varieties that can be grown and sold. Thus growers are increasingly interested in conferring particular traits of interest (e.g., drought tolerance) through grafting onto rootstocks. A major goal is to develop rootstocks that can influence scion growth and productivity under drought; particularly those that can increase water conservation through reducing the need for irrigation while ameliorating negative impacts on yields. Growers and scientists recognize that rootstocks have a profound influence on vine physiology (e.g., stomatal conductance, photosynthesis, water status), productivity (e.g., growth, fruit yields, fruit composition), and drought resistance. The challenge is to better understand the exact mechanisms through which rootstocks manifest these effects and thus build the knowledge necessary to drive the development of rootstocks with predictable effects on the scion. The aim of this review is to explore our current understanding of the mechanisms by which grapevine rootstocks influence scion growth and stress response; specifically focused on the integration of vine growth and productivity under water deficit