What is the role of water potential in the movement of water throughout the plant body?

Question

What is the role of water potential in the movement of water throughout the plant body?

Answer 1

Water transported up from the roots must replace water lost by transpiration.  Xylem sap rises against gravity, driven by a gradient of water potential. Water flows from an area of high potential to an area of low potential. Water Potential is expressed in units of pressure: 1 bar is the pressure needed to push up a column of water 10 meters. 1 megapascal = 10 bars. Pure water has a potential of 0. Addition of pressure increases water potential. Addition of solutes decreases it.  When transpiration is low, ions pumped into the stele decrease water potential and cause water uptake by the stele. This uptake force is called root pressure. It Cannot keep pace with transpiration, and can only force water up a few meters.

Answer 2

The difference between the free energy of water molecule in pure water and to that of solution is called water potential

The water potential in pure water is maximum, it is zero.

In solutions the water potential is -ve value.

The difference in this  makes the solvent to get osmosis. this results in movement of water in plant body