Water Redistribution Evaluated by Weighting Lysimeters in Olive Split-Root Systems

Hydraulic redistribution (HR) in plants facilitates bidirectional water transport through the vascular system in response to soil water potential gradients, enabling water movement from deeper to shallower soil layers or vice versa, with implications for ecological facilitation. This study aimed to evaluate the efficacy of high-precision weighing lysimeters in detecting HR in olive (Olea europaea L.) using a split-root experimental setup with potted trees. Sixteen pots, each containing half of a plant's root system, were independently monitored for mass changes to quantify water transfer between irrigated and water-stressed compartments. The purposedly built precision lysimeter array effectively isolated weights despite mechanical connections between pot pairs. Results demonstrated measurable water redistribution via roots from irrigated to dry pots and highlighted the potential of the lysimeters for precise quantification of plant-mediated water dynamics. It was observed that water transfer intensity peaked shortly after irrigation and diminished over time, with pronounced effects observed during nocturnal periods or cloudy humid daily conditions. These findings confirm previous data observed with reverse flow sap flow sensors and advance understanding of HR in olive agricultural systems.