The goal of this study was to assess the effect of induced embolism with air injection treatments on the function of xylem in Acer rubrum L. and Salix nigra Marsh. Measurements made on mature trees of A. rubrum showed that pneumatic pressurization treatments that created a pressure gradient of 5.5 MPa across pit membranes (ΔPpit) had no effect on stomatal conductance or on branch-level sap flow. The same air injection treatments made on 3-year-old potted A. rubrum plants also had no effect on whole plant transpiration. A separate study made on mature A. rubrum trees showed that 3.0 and 5.5 MPa of ΔPpit values resulted in an immediate 100% loss in hydraulic conductance (PLC) in petioles. However, the observed change in PLC was short lived, and significant hydraulic recovery occurred within 5–10 min post air-pressurization treatments. Similar experiments conducted on S. nigra plants exposed to ΔPpit of 3 MPa resulted in a rapid decline in whole plant transpiration followed by leaf wilting and eventual plant death, showing that this species lacks the ability to recover from induced embolism. A survey that measured the effect of air-pressurization treatments on seven other species showed that some species are very sensitive to induction of embolism resulting in leaf wilting and branch death while others show minimal to no effect despite that in each case, the applied ΔPpit of 5.5 MPa significantly exceeded any native stress that these plants would experience naturally.
Keywords: embolism refilling, air-pressurization, hydraulic conductivity, Granier sap flow probes, xylem
Citation: Melcher PJ and Zwieniecki MA (2013) Functional analysis of embolism induced by air injection in Acer rubrum and Salix nigra. Front. Plant Sci. 4:368. doi: 10.3389/fpls.2013.00368
Received: 21 June 2013; Paper pending published: 24 July 2013;
Accepted: 29 August 2013; Published online: 24 September 2013.
Edited by:Abraham D. Stroock, Cornell University, USA
Reviewed by:Lars Hendrik Wegner, Karlsruhe Institute of Technology, Germany
Copyright © 2013 Melcher and Zwieniecki. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Peter J. Melcher, Department of Biology, Ithaca College, 953 Danby Road, Ithaca, NY 14850, USA email: firstname.lastname@example.org