Plant-Based Approaches to Deficit Irrigation in Trees and Vines

Field experiments have been performed on grapevine as well as a number of woody tree species (almond, prune, pear, cherry) to determine the relation of plant water potential to a number of indices of plant physiological activity (leaf conductance, vegetative growth and fruit growth and composition).  Horticultural benefits of regulated deficit irrigation (RDI) have been documented in many crops (grapevine, almond, prune, cherries), but management of irrigation to achieve these benefits is difficult without a reliable plant-based measure of stress.  Midday stem water potential (SWP) has proven to be a robust, reliable, and practical measure of stress, and closely related to physiological responses at the leaf and whole plant level (stomatal conductance, vegetative growth, and fruit growth and composition such as soluble solids and fruit color).  Attempts are currently underway to estimate SWP from remotely and locally sensed parameters such as canopy temperature and canopy spectral characteristics.