Refer to the figure.

- In soil, there can be layers with more or less available water. In the figure, there is a lower water potential in shallow soils than in deep soils. Considering this scenario, what will the stem water potential be in the middle of the night and why?
A) -3.0 MPa because the plant will equilibrate with the lowest water potential.
B) -0.5 MPa because the plant will equilibrate with the highest water potential.
C) Between -3.0 MPa and -0.5 MPa because the plant will average across all available water.
D) Between -3.0 MPa and -0.5 MPa because some of the water from the deep soil layers will move through the roots and then into the dry, shallow soils.

Question

Refer to the figure.

- In soil, there can be layers with more or less available water. In the figure, there is a lower water potential in shallow soils than in deep soils. Considering this scenario, what will the stem water potential be in the middle of the night and why?
A) -3.0 MPa because the plant will equilibrate with the lowest water potential. 
B) -0.5 MPa because the plant will equilibrate with the highest water potential. 
C) Between -3.0 MPa and -0.5 MPa because the plant will average across all available water. 
D) Between -3.0 MPa and -0.5 MPa because some of the water from the deep soil layers will move through the roots and then into the dry, shallow soils.

Quizplus · Accepted Answer

At night, when transpiration is low, water can move from areas of higher potential (deep soil) to areas of lower potential (shallow soil), leading to an intermediate stem water potential.

Refer to the Figure