This study reports experimental evidence for light-mediated changes of stem hydraulic conductance (Kstem) in field-grown laurel plants. Field measurements based on the evaporative flux method revealed that sun-exposed branches had 60% higher Kstem with respect to shade-exposed branches. Xylem sap potassium concentration was ∼3 mM as recorded in shaded branches and up to 12 mM in illuminated ones. Such a difference in [K+] proved to induce significant increase in xylem hydraulic conductance of excised twigs when artificially perfused with various solutions, as a likely consequence of the interaction of cations with the pectic matrix of pit membranes (the so-called ‘ionic effect’). We propose that this mechanism provides plants with a large potential for fine regulation of water flow towards different parts of the canopy exposed to different environmental conditions with the result of optimizing light and water utilization.
Titolo: | Changes of xylem sap ionic content and stem hydraulics in response to irradiance in Laurus nobilis |
Autori: | |
Data di pubblicazione: | 2010 |
Rivista: | |
Abstract: | This study reports experimental evidence for light-mediated changes of stem hydraulic conductance (Kstem) in field-grown laurel plants. Field measurements based on the evaporative flux method revealed that sun-exposed branches had 60% higher Kstem with respect to shade-exposed branches. Xylem sap potassium concentration was ∼3 mM as recorded in shaded branches and up to 12 mM in illuminated ones. Such a difference in [K+] proved to induce significant increase in xylem hydraulic conductance of excised twigs when artificially perfused with various solutions, as a likely consequence of the interaction of cations with the pectic matrix of pit membranes (the so-called ‘ionic effect’). We propose that this mechanism provides plants with a large potential for fine regulation of water flow towards different parts of the canopy exposed to different environmental conditions with the result of optimizing light and water utilization. |
Handle: | http://hdl.handle.net/11570/1902115 |
Appare nelle tipologie: | 14.a.1 Articolo su rivista |