How timing of stem girdling affects needle xylem structure in Scots pine

While needles represent a proportionally large fraction of whole-plant hydraulic resistance, no studies to date have investigated how source–sink disturbances affect needle xylem structure. In this study, we evaluated structural changes in xylem in current-year needles of Scots pine 227 and 411 days...

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Bibliographic Details
Published in:European journal of forest research 2018-02, Vol.137 (1), p.57-67
Main Authors: Gebauer, Roman, Plichta, Roman, Bednářová, Emilie, Foit, Jiří, Čermák, Václav, Urban, Josef
Format: Article
Language:English
Subjects:
Biomedical and Life Sciences
Empirical equations
Flowers & plants
Forestry
Gas exchange
Girdling
Hydraulic equipment
Hydraulics
Life Sciences
Mathematical models
Original Paper
Pine
Pine needles
Pine trees
Pinus sylvestris
Plant Ecology
Plant Sciences
Trees
Xylem
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Summary:While needles represent a proportionally large fraction of whole-plant hydraulic resistance, no studies to date have investigated how source–sink disturbances affect needle xylem structure. In this study, we evaluated structural changes in xylem in current-year needles of Scots pine 227 and 411 days after stem girdling (hereafter referred to as DAG). Maximum and minimum tracheid lumen diameters and therefore also the size of tracheid lumen areas increased in needles 227 DAG compared to control needles. In contrast, tracheid dimensions were similar in needles 411 DAG as in the control needles, but smaller xylem area and lower number of tracheids resulted in the lower theoretical needle hydraulic conductivity of those needles. Several needle xylem parameters were intercorrelated in both control and girdled trees. These observed changes provide a new understanding of the processes that occur following a source–sink disturbance. Considering anatomical parameters such as the number of tracheids, tracheid dimension, or needle xylem area, which are rarely described in physiological studies, could be helpful, for example, in understanding to tree hydraulic systems or for modeling gas exchange. Finally, empirical equations were developed to calculate needle theoretical hydraulic conductivity and the number of tracheids in needles using an easily measurable parameter of needle xylem area.
ISSN:1612-4669
1612-4677
DOI:10.1007/s10342-017-1090-z