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Abstract Detail


Water Relations

Lambeth, Emily [1], Stiller, Volker [2].

The Effects of Salinity on Xylem Cavitation in 1-yr old Baldcypress (Taxodium distichum) Seedlings.

In the past, considerable efforts have been undertaken to restore Baldcypress (Taxodium distichum) around Lake Pontchartrain in Southeastern Louisiana. Vast amounts of cypress trees have been planted with varying rates of success. Increased salinity is often cited as one reason for the high tree mortality. The aim of this study was to investigate the effects of increased salinity on xylem vulnerability to cavitation. One-year old, bare rooted seedlings were grown in the greenhouse of Southeastern Louisiana University. After plants were established, half of the trees were irrigated twice daily with salt water; the other half (control) was irrigated with fresh water. The concentration of the salt solution was gradually raised over a 8-week period from 2ppt to 8ppt and was then kept constant at 8ppt for the remainder of the experiment (10 weeks). Throughout the growing season, transpiration rates, stomatal conductances, and relative diameter growth rates were monitored. At the end of the growing season, plants were harvested and vulnerability curves were measured on current year stem segments. Salinity reduced transpiration rates and stomatal conductances approximately by half (E = 2.5±0.8 and 4.7±1.0 mmol s-1 s-2; gS = 215±64 and 436±127 mmol s-1 s-2 for salt and control plants, respectively. Mean±SD, n = 5). Reduced transpiration rates were mirrored by lower relative diameter growth rates in salt treated plants (RGR= 0.09±0.03 mm/mm and 0.15±0.07 mm/mm for salt and control plants respectively. Mean±SD, n = 9). Vulnerability curves showed that P50s of salt treated plants were significantly lower (2.57 MPa) compared to control plants (2.25 MPa, n=9, p<0.001, F-test). Although P50 and RGR were measured on the same plants, the two parameters were not correlated.


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1 - Southeastern Louisiana University, Department of Biological Sciences
2 - Southeastern Louisiana University, Department of Biological Sciences, SLU Box 10736, Hammond, Louisiana, 70402, USA

Keywords:
xylem vulnerability
salinity
bald cypress
Taxodium distichum.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P09026
Abstract ID:2702


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