Figure 1.

Schematic representation of the system designed to (1) infuse different solutions into grapevine stems without interrupting the water flow and (2) measure water flow rate through the stems. Compressed air pressurizes the water container (A); two pressure gauges (B) in series are used to keep a constant pressure during the experiments. The basal end of the stem is attached to plastic tubing and to a set of three-way valves and loops (C) used to introduce particles, enzymes, chelator, or carbohydrates into the water flow. The distal end of the stem explant (actually its more apical end) is fitted into plastic tubing to facilitate the collection of eluent using a fraction collector (D). The water container is on top of an electronic balance (E) that is connected to a computer (F) programmed to automatically record the weight change of the container every 15 s. The water reservoir and the electronic balance were placed inside a cardboard box (G) fixed to the bench surface, providing a shield from air currents and limiting vibrations.