Journal Article

Root carbon reserve dynamics in aspen seedlings: does simulated drought induce reserve limitation?

David A. Galvez, S.M. Landhäusser and M.T. Tyree

Edited by Michael Ryan

in Tree Physiology

Volume 31, issue 3, pages 250-257
Published in print March 2011 | ISSN: 0829-318X
Published online March 2011 | e-ISSN: 1758-4469 | DOI: http://dx.doi.org/10.1093/treephys/tpr012
Root carbon reserve dynamics in aspen seedlings: does simulated drought induce reserve limitation?

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In a greenhouse study we quantified the gradual change of gas exchange, water relations and root reserves of aspen (Populus tremuloides Michx.) seedlings growing over a 3-month period of severe water stress. The aim of the study was to quantify the complex interrelationship between growth, water and gas exchange, and root carbon (C) dynamics. Various growth, gas exchange and water relations variables in combination with root reserves were measured periodically on seedlings that had been exposed to a continuous drought treatment over a 12-week period and compared with well-watered seedlings. Although gas exchange and water relations parameters significantly decreased over the drought period in aspen seedlings, root reserves did not mirror this trend. During the course of the experiment roots of aspen seedlings growing under severe water stress showed a two orders of magnitude increase in sugar and starch content, and roots of these seedlings contained more starch relative to sugar than those in non-droughted seedlings. Drought resulted in a switch from growth to root reserves storage which indicates a close interrelationship between growth and physiological variables and the accumulation of root carbohydrate reserves. Although a severe 3-month drought period created physiological symptoms of C limitation, there was no indication of a depletion of root C reserve in aspen seedlings.

Keywords: carbon limitation; native percentage loss of conductivity; non-structural carbohydrates; Populus tremuloides; starch; xylem cavitation

Journal Article.  5015 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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