1. UNI Plant Physiology Spring 2010
Hydraulic Lift
UNI Plant Physiology
Spring 2010

2. Deep and shallow roots (or deep roots only)
Observations I
Deep and shallow roots (or deep roots only)
Shallow roots

3. Observations II
Small, shallow rooted plants near plants with both deep and shallow roots
Surrounding soil bare
Especially seen with limited soil moisture

4. Explanations
Old version: larger plant shaded smaller one, kept it from losing so much water
New version
Shade still counts
Additional source of water: hydraulic lift
Big plant “waters” small plant at night

5. Day dawns
Light and temperature increase, stomata open, and transpiration begins.
Water is pulled up the trunk from the roots.
Shallow rooted plants transpire, with water moving from surface soil to roots.
Transpiration stops in the shallow rooted plant.
Water moves into surface roots from surface soil.
As transpiration continues, the surface soil dries out.
Water moves into the roots from the soil.

6. Night falls Transpiration stops when light levels decrease.
Hours later, the surface soil has been rehydrated via the roots.
Water moves from the wet roots to the dry surface soil.
Groundwater moves into deeper roots.

7. Evidence Root depths need to be right Groundwater must be present
Soil samples change moisture the right way through day and night
Transpired water
Rainwater and groundwater are different (isotope ratios)
We see groundwater transpired by small plant

8. Hydraulic lift Groundwater to shallow rooted plants
When little surface water available
Uses plants with deep and shallow roots
Not dew making this soil moist at night
Another cool water relations story

9. 2008