Question

What are the components of water potential and what factors influence each factor? (be sure to outline the equation for water potential, and describe factors influencing each)

Answer 1

Water potential is a measure of the potential energy in water, or the difference in potential energy between a given water sample and pure water, when atmospheric pressure and temperature are kept the same.. There are 3 components in water potential namely:

(1) Pressure potential: is the difference between pressure of the water and that of the atmosphere;

(2) Osmotic pressure (solute potential): refers to the reduction in water potential due to the presence of dissolved solutes; and

(3) Matric Potential (in soil): affects adhesion of sticking water to soil surfaces. This shows how likely it is water to becomes unstruck.

(4) gravitational potential: force of gravity pulling on the water

So, total water potential is given by:

Total water potential = matric potential + osmotic/solute potential+ pressure/turgor potential+gravitational potential

Factors affecting water potential:

Concentration or chemical potential: Water will diffuse from a dilute solution to concentrated solution (osmosis)

Pressure (mechanical potential): water will flow from a high pressure system to a low pressure system.

Height (gravitational potential):water flows downhill

Charge (electrical potential): may be ignore since water is uncharged.