This Article Full Text Full Text (PDF) All Versions of this Article: 140/1/374    most recent pp.105.067900v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (8) Citing Articles via Google Scholar Google Scholar Articles by Pittermann, J. Articles by Sperry, J. S. Search for Related Content PubMed PubMed Citation Articles by Pittermann, J. Articles by Sperry, J. S. Agricola Articles by Pittermann, J. Articles by Sperry, J. S. Related Collections Biology of Transpiration

WHOLE PLANT AND ECOPHYSIOLOGY

Analysis of Freeze-Thaw Embolism in Conifers. The Interaction between Cavitation Pressure and Tracheid Size¹

Department of Biology, University of Utah, Salt Lake City, Utah 84112

Ice formation in the xylem sap produces air bubbles that under negative xylem pressures may expand and cause embolism in the xylem conduits. We used the centrifuge method to evaluate the relationship between freeze-thaw embolism and conduit diameter across a range of xylem pressures (P_x) in the conifers Pinus contorta and Juniperus scopulorum. Vulnerability curves showing loss of conductivity (embolism) with P_x down to –8 MPa were generated with versus without superimposing a freeze-thaw treatment. In both species, the freeze-thaw plus water-stress treatment caused more embolism than water stress alone. We estimated the critical conduit diameter (D_f) above which a tracheid will embolize due to freezing and thawing and found that it decreased from 35 µm at a P_x of –0.5 MPa to 6 µm at –8 MPa. Further analysis showed that the proportionality between diameter of the air bubble nucleating the cavitation and the diameter of the conduit (kL) declined with increasingly negative P_x. This suggests that the bubbles causing cavitation are smaller in proportion to tracheid diameter in narrow tracheids than in wider ones. A possible reason for this is that the rate of dissolving increases with bubble pressure, which is inversely proportional to bubble diameter (La Place's law). Hence, smaller bubbles shrink faster than bigger ones. Last, we used the empirical relationship between P_x and D_f to model the freeze-thaw response in conifer species.

² Present address: Department of Integrative Biology, University of California, 4007 Valley Life Sciences Bldg., Berkeley, CA 94720.

³ Present address: Department of Biology, University of Utah, Salt Lake City, UT 84112.

The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Jarmila Pittermann (pittermann{at}berkeley.edu).

Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.105.067900.

^* Corresponding author; e-mail pittermann{at}berkeley.edu; fax 510–643–6264.

Received June 30, 2005; returned for revision September 27, 2005; accepted October 26, 2005.

This article has been cited by other articles:

				A. R. Cobb, B. Choat, and N. M. Holbrook Dynamics of freeze-thaw embolism in Smilax rotundifolia (Smilacaceae) Am. J. Botany, April 1, 2007; 94(4): 640 - 649. [Abstract] [Full Text] [PDF]

				S. Mayr, H. Cochard, T. Ameglio, and S. B. Kikuta Embolism Formation during Freezing in the Wood of Picea abies Plant Physiology, January 1, 2007; 143(1): 60 - 67. [Abstract] [Full Text] [PDF]

				J. S. Sperry, U. G. Hacke, and J. Pittermann Size and function in conifer tracheids and angiosperm vessels Am. J. Botany, October 1, 2006; 93(10): 1490 - 1500. [Abstract] [Full Text] [PDF]