Evaluating Water Use Strategies in Olive Trees Grown under Different Water Availability Regimes through an Integrated Approach of Sap Flow and High Resolution Stem Growth Analysis

The effect of different water availability regimes on several plant water status indicators was studied in order to assess water consumption and drought adaptation in Olea europaea growing in an experimental site plantation in southern Italy (41°06’N, 14°43’E; at an elevation of 250 m a.s.l.). The study was carried out on mature olive plants, subjected to different water availability since 1994. Treatments were a rainfed (non-irrigated) and fully irrigated regime (100% of ETc throughout the irrigation season). During the growing season 2007, plants were continuously monitored by automatic point dendrometers measuring stem radius variation. Whole-plant water use was determined using a xylem sap flow method (compensation heat-pulse technique). Additional ecophysiological parameters, such as stomatal conductance and water potential were periodically measured, as well as vegetative development and biochemical characteristics. Stem Maximum Daily Shrinkage (MDS) and sap flux were also compared. Results were evaluated to investigate water use strategies, functional, and structural acclimation to watering. These observations were analysed to identify valuable parameters that may be used to implement automatic management irrigation practices in olive tree plantations.