ARS | Publication request: VULNERABILITY TO CAVITATION IN GRAPEVINES HAS BEEN OVERESTIMATED BY THE CENTRIFUGE TECHNIQUE

Submitted to: Plant Cell and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 1, 2010
Publication Date: April 22, 2010
Citation: Choat, B., Drayton, W., Brodersen, C., Matthews, M., Shackel, K., Wada, H., Mcelrone, A.J. 2010. MEASUREMENT OF VULNERABILITY TO WATER STRESS-INDUCED CAVITTION IN GRAPEVINE: A COMPARISON OF FOUR TECHNIQUES APPLIED TO A LONG-VESSELED SPECIES. Plant Cell and Environment. doi: 10-1111/j.1365-3040.

Technical Abstract: Grapevines are considered among the most vulnerable woody plant species to water stress-induced cavitation with embolism forming at slight tensions. However, we found that native embolism in stems of field grown Vitis vinifera cv. Chardonnay never exceeded 30% despite xylem water potentials ('x) reaching -1.33 MPa. The discrepancy between these native embolism measurements and those of previous reports, led us to assess four separate methods commonly used to test vulnerability of woody plant stems to water stress-induced cavitation. Centrifuge, dehydration, and air-injection methods, which rely on measurement of percentage loss of hydraulic conductivity (PLC) in detached stems, were compared against non-invasive monitoring of xylem cavitation with Nuclear Magnetic Resonance (NMR) imaging. The results indicated that the centrifuge technique significantly over estimated vulnerability to cavitation compared with dehydration and air-injection techniques. The centrifuge method indicated that stems reached 90% loss of conductivity at stem xylem water potentials ('x) of -1.5 MPa, while the dehydration and air-injection measurements indicated that no significant embolism occurred above (less negative hydrostatic pressures) 'x of -2.0 MPa. Observations with NMR agreed with the dehydration and air injection methods, showing that the majority of vessels were still water filled above 'x of -1.5 MPa. The results of NMR and native embolism measurements indicate that vulnerability curves generated by dehydration and air-injection are more suitable for species with long vessels than the centrifuge technique. Our findings show V. vinifera stems are far-less vulnerable to water stress-induced cavitation than previously reported.