Abstract Detail

Physiological Section

Melcher, Peter [1], Zwieniecki, Maciej [2], Holbrook, N. Michele [3].

Functional embolism refilling in red maple (Acer rubrum L.).

The goal of this study was to assess the ability of mature trees and saplings of Acer rubrum L. to refill artificially embolized vessels in intact branches. Embolism was induced by injecting air (4.5 MPa) into the stem. Following the air-injection treatment, changes in the stems capacity to transport water were determined using grainer-style sap-flow probes inserted into branches located about 1-m distally to the point of air injection. Sap flow was measured continuously over many days following air injection. No measurable effect from air injection on the flow of sap was observed. Air injection also had no effect on stomatal conductance and leaf water potentials. Injecting air at 5.5 MPa pressure into the main stems of potted, three-year-old saplings also had no immediate or prolonged effects on whole plant transpiration. Regression analysis revealed that whole plant transpirational flow rates were either the same, or even greater after air injection than prior to injection treatment. We also measured changes in petiole hydraulic conductivity (Kpet) following air-injection pressures of 0, 3.0 or 5.5 MPa to assess if air-injection treatments resulted in embolisms within petioles. Kpet was found to be reduced to values near zero immediately following air injection into stems (at time zero). However, Kpet completely recovered within 2½ minutes on petioles that had their branches subjected to the 3.0 MPa air injection treatments and it took about 5 to 10 minutes to restore Kpet to 70 % of the initial Kpet values in petioles attached to branches injected with 5.5 MPa of gas pressure. These studies provide further evidence that embolism refilling can occur in tree species when plants are actively transpiring and under negative water potentials. Although we should be aware that the air injection method may cause artificial conditions that do not exist in nature and may result in artifacts that potentially skew our assessment of embolism refilling.

Broader Impacts:

1 - Ithaca College, Biology, 953 Danby Road, Center for Natural Sciences, Ithaca, NY, 14850, United States
2 - Arnold Arboretum of Harvard University, Jamaica Plain, MA, 02130, USA
3 - Harvard University, Department of Organismic and Evolutionary Biology, 16 Divinity Avenue, Biological Laboratories, Cambridge, MA, 02138, USA

Keywords:
xylem
embolism refilling
air injection
red maple.

Presentation Type: Oral Paper:Papers for Sections
Session: 30
Location: Westminster Room/Chase Park Plaza
Date: Tuesday, July 12th, 2011
Time: 11:35 AM
Number: 30012
Abstract ID:717