Grapevine sensitivity to water stress

摘要

Cluster sensitivity to water stress occurring at different stages of berry growth is reviewed with the aim of delivering guidelines for an improved use of irrigation water. Hydraulic communication between shoots and green berries is active as shownby similar water potentials. Furthermore xylem water backflow from the cluster into the shoots has been ascertained in the presence of water stress. Thus, green berries appear very sensitive to water stress which often brings about yield reduction (moresevere if water shortage occurs during the cell-division growth stage) and poor grape quality. Post-veraison berries acquire a certain resistance to desiccation, which also parallels progressive impairing of xylem conductance at the berry pedicel. As matter of fact, berry water supply during ripening is primarily provided through the phloem. Berry water status after veraison would therefore allow tolerance for a soil water stress whose length and severity needs to be assessed depending upon canopy assimilation capacity versus amount of crop. For example, a water stress induced on a vine already carrying a high crop could result in a limitation of leaf function down to the point where berry ripening is incomplete or delayed. If the soil water stress issuperimposed on vines having adequate source potential with respect to the yield, the reduction in canopy assimilation might not be severe enough to compromise final grape maturity.