Leaf Water Potential
LWP measured as negative pressure (tension) in bars. One bar is ~ 15 psi tension.
Amount of tension (LWP) depends on:
- soil moisture (res. from soil to root).
- resistance to move from root surface to water conducting vessels (xylem).
- resistance to flow through the xylem up the plant.
- resistance from xylem to leaf cells.
- Resistance to water loss from stomates depending on degree of opening.
Afternoon wilting ~ 20 bars