Do ray cells provide a pathway for radial water movement in the stems of conifer trees?
• Premise of the study: The pathway of radial water movement in tree stems presents an unknown with respect to whole-tree hydraulics. Radial profiles have shown substantial axial sap flow in deeper layers of sapwood (that may lack direct connection to transpiring leaves), which suggests the existenc...
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| Vydané v: | American journal of botany Ročník 100; číslo 2; s. 322 - 331 |
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| Hlavní autori: | , , , , |
| Médium: | Journal Article |
| Jazyk: | English |
| Vydavateľské údaje: |
United States
Botanical Society of America
01.02.2013
Botanical Society of America, Inc |
| Predmet: | |
| ISSN: | 0002-9122, 1537-2197, 1537-2197 |
| On-line prístup: | Získať plný text |
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| Shrnutí: | • Premise of the study: The pathway of radial water movement in tree stems presents an unknown with respect to whole-tree hydraulics. Radial profiles have shown substantial axial sap flow in deeper layers of sapwood (that may lack direct connection to transpiring leaves), which suggests the existence of a radial pathway for water movement. Rays in tree stems include ray tracheids and/or ray parenchyma cells and may offer such a pathway for radial water transport. This study investigated relationships between radial hydraulic conductivity (ks-rad) and ray anatomical and stem morphological characteristics in the stems of three conifer species whose distributions span a natural aridity gradient across the Cascade Mountain range in Oregon, United States.• Methods: The ks-rad was measured with a high-pressure flow meter. Ray tracheid and ray parenchyma characteristics and water transport properties were visualized using autofluorescence or confocal microscopy.• Key results: The ks-rad did not vary predictably with sapwood depth among species and populations. Dye tracer did not infiltrate ray tracheids, and infiltration into ray parenchyma was limited. Regression analyses revealed inconsistent relationships between ks-rad and selected anatomical or growth characteristics when ecotypes were analyzed individually and weak relationships between ks-rad and these characteristics when data were pooled by tree species.• Conclusions: The lack of significant relationships between ks-rad and the ray and stem morphologies we studied, combined with the absence of dye tracer in ray tracheid and limited movement of dye into ray parenchyma suggests that rays may not facilitate radial water transport in the three conifer species studied. |
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| Bibliografia: | http://dx.doi.org/10.3732/ajb.1200333 The authors thank Cascade Timber Consulting for supply of study material; P. Denne for discussion, B. Barnard for assistance with data collection, and D. Barnard for helpful comments. This work was supported in part by the U. S. Department of Agriculture Wood Utilization Research Special Grant to Oregon State University, by National Science Foundation (09‐19871) and Joint Venture Agreement (07‐JV‐468) with the U. S. Department of Agriculture, Forest Service Pacific Northwest Research Station. SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 14 ObjectType-Article-1 ObjectType-Feature-2 content type line 23 |
| ISSN: | 0002-9122 1537-2197 1537-2197 |
| DOI: | 10.3732/ajb.1200333 |