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- Title
Xylem pressure response in maize roots subjected to osmotic stress: determination of radial reflection coefficients by use of the xylem pressure probe.
- Authors
Zhu, J. J.; Zimmermann, U.; Thurmer, F.; Haase, A.
- Abstract
The absolute pressure in conducting xylem vessels of roots of 2-week-old, slowly transpiring intact maize plants (bathed in nutrition medium) was determined to be +0024 ± 0.044 MPa using the xylem pressure probe. When the roots were subjected to osmotic stress (NaCl, KCl or sucrose), the xylem pressure decreased immediately and became more negative. However, the response of xylem pressure to osmotic stress was considerably attenuated, indicating that the radial reflection coefficients, σr of the maize root for these solutes were rather low (between 0.2 and 0.4 depending on the concentration of the osmoticum). The low values of σr. may be caused (partly) by unstirred layer effects. In repeated osmoticum/nutrition regimes a complex pattern of changes in xylem pressure was observed which was apparently linked to the interplay between transpiration and (passive and/or active) solute loading of the xylem. These processes were not observed when the roots were subjected to osmotic stress after excision. In this case, a biphasic response was observed comparable to that found for excised roots using the root pressure probe.
- Subjects
XYLEM; PLANT cells &; tissues; PLANT roots; PLANT transpiration; CORN; REFLECTANCE; PLANT-water relationships
- Publication
Plant, Cell & Environment, 1995, Vol 18, Issue 8, p906
- ISSN
0140-7791
- Publication type
Article
- DOI
10.1111/j.1365-3040.1995.tb00599.x