NEGATIVE XYLEM PRESSURES IN PLANTS - A TEST OF THE BALANCING PRESSURE TECHNIQUE

Xylem tension was experimentally imposed by centrifugal force to assess the stability of negative pressures within the xylem and the estimation of those pressures with a pressure chamber. Balancing pressure measurements of leaves attached to a spinning branch at the axis of rotation closely agreed with tensions calculated from the rotational velocity. This agreement demonstrates that the xylem is capable of sustaining large negative pressures and directly validates the balancing pressure technique.