Temperature effects on hydraulic conductance and water relations of Quercus robur L.
Résumé
The effects of temperature on root and shoot hydraulic conductances (g shoot and g root) were investigated for Quercus robur L. saplings. In a first experiment, conductances were measured with a High Pressure Flow Meter on excised shoots and detopped root systems. The g root and g shoot increased considerably with temperature from 0-50°C. Between 15°C and 35°C, g shoot and g root varied with water viscosity. In a second experiment, the impact of temperature-induced changes in g root on sapling transpiration (E) and leaf water potential (leaf) was assessed. Intact plants were placed in a growth cabinet with constant air and variable soil temperatures. E increased linearly with soil temperature but leaf remained constant. As a consequence, a linear relationship was found between E and g plant. The results illustrate the significance of g plant for the stomatal control of transpiration and the signifiance of temperature for tree weter transport.