© 1989 Heron Publishing—Victoria, Canada
Ultrasound emission after cycles of water stress in Picea abies
M. Borghetti (1), A. Raschi (2) and J. Grace (3)
1. lstituto Miglioramento genetico delle piante forestali, CNR, via S. Bonaventura 13, 50145-Firenze, Italy / 2. Istituto Analisi ambientale e telerilevamento applicati all’agricolura, CNR, P. le delle Cascine 18, 50144-Firenze, Italy / 3. Department of Forestry and Natural Resources, University of Edinburgh, The King’s Buildings, Edinburgh EH9 3JU, UK / Received July 22, 1988
Summary
The relationships among rate of ultrasound acoustic emission (AE), xylem water potential and transpiration rate were investigated
in 5-year-old potted saplings of Picea abies Karst. after cycles of water stress. Water-stressed plants displayed minimum xylem water potentials of –3.9 MPa, near-zero
transpiration rates and up to 45 AE counts per minute. After rewatering, water-stressed plants no longer produced AEs. Well-watered
control plants produced only a small number of ultrasonic AEs. After three cycles of water stress (lasting 24 days in total),
it was estimated that about two-thirds of the functional tracheids were embolized. The concomitant reduction in hydraulic
conductance was about 70%.
