Root hydraulic conductivity and xylem sap levels of zeatin riboside and abscisic acid in ectomycorrhizal Douglas fir seedlings

doi:10.1111/j.1469-8137.1990.tb00453.x

If you are seeing this message, you may be experiencing temporary network problems. Please wait a few minutes and refresh the page. If the problem persists, you may wish to report it to your local Network Manager.

It is also possible that your web browser is not configured or not able to display style sheets. In this case, although the visual presentation will be degraded, the site should continue to be functional. We recommend using the latest version of Microsoft or Mozilla web browser to help minimise these problems.

Systems Maintenance, Monday, 15th February 2010

Wiley InterScience

New Phytologist

Volume 115 Issue 2, Pages 275 - 284

Published Online: 28 Apr 2006

Published on behalf of the New Phytologist Trust

Go to New Phytologist Trust

< Previous Abstract | Next Abstract >

Save Article to My Profile Download Citation Request Permissions

Abstract | References | Full Text: PDF (Size: 13631K) | Related Articles | Citation Tracking

Root hydraulic conductivity and xylem sap levels of zeatin riboside and abscisic acid in ectomycorrhizal Douglas fir seedlings

MARK D. COLEMAN ¹ *, CAROLINE S. BLEDSOE ¹ BARBARA A. SMIT ¹

¹ College of Forest Resources, University of Washington, Seattle, WA 98195, USA

*United States Department of Agriculture, Forestry Sciences Laboratory, P.O. Box 898, Rhinelander, WI 54501.

KEYWORDS

Abscisic acid • zeatin riboside • diurnal root conductance • ectomycorrhizas • phosphorus • root hydraulic conductivity

ABSTRACT

Mechanistic hypotheses to explain mycorrhizal enhancement of root hydraulic conductivity (L_p) suggest that phosphorus (P) nutrition, plant growth substances and/or altered morphology may be responsible. Such ideas are based on work with VA (vesicular-arbuscular) mycorrhizas. Since VA mycorrhizas and ectomycorrhizas differ in many respects, they may alter host plant water uptake via different mechanisms. This paper examines L_T in various ectomycorrhizal associations while considering factors which are important to the VA mycorrhizal effect on L_p. Douglas fir Pseudotsuga menziesii (Mirb.) Franco] seedlings inoculated with the ectomycorrhizal fungi Laccaria bicolor (Maire) Orton and Hebeloma crustuliniforme (Bull, ex St. Amans) Quel. and non-inoculated seedlings infected naturally with Thelephora were grown under three low levels of P fertilization (1, 10 and 100 fim P). Seedling morphology, tissue P levels, L_p and plant growth substance levels in xylem sap were measured after nine months growth. Increased tissue P and decreased root/shoot ratio correlated with increased L_p in each of the mycorrhizal treatments. When adjusted for the effect of these two factors, L_p of Laccaria and Hebeloma seedlings was still lower than the Thelephora seedlings. In a subsequent experiment, the L_p of seedlings with Hebeloma and Rhizopogon vinicolor Smith mycorrhizas was compared to the L_p of non-mycorrhizal seedlings (grown at 100 mM P) and no differences were found among treatments. The lack of an ectomycorrhizal effect on L_p is quite different from the enhancement of host L_p by VA mycorrhizas. Zeatin riboside concentrations of Thelephora- and Hebeloma-iniected seedlings were similar, yet higher than with Laccaria. There was no relationship between plant growth substances and L_p in ectomycorrhizal Douglas fir, despite lower zeatin riboside concentrations for Laccaria-inoculated plants.