Water Potential Calculator
Calculate the total water potential of plant cell zones using solute and pressure equations.
Plant Cell Parameters
Enter solute concentration, temperature, and pressure.
Water Potential (Ψ)
Direction of Osmosis
Water moves spontaneously toward areas with lower (more negative) total water potential.
Water Potential Values in Plant-Soil-Atmosphere Continuum Reference
| System Component | Water Potential (bars) | Water Potential (MPa) | Physiological Status |
|---|---|---|---|
| Pure Water / Moist Soil | 0.0 to -1.5 bars | 0.0 to -0.15 MPa | Optimal root water availability |
| Turgid Leaf Cell | -2.0 to -8.0 bars | -0.20 to -0.80 MPa | Healthy turgor pressure maintained |
| Wilted Leaf (Wilting Point) | -15.0 bars | -1.50 MPa | Permanent wilting point (turgor = 0) |
Methodology & Equations
van 't Hoff Osmotic Equation
Where $R = 0.0831$ L·bar/(mol·K) and $T = °C + 273.15$ K.
Total Water Potential
Combines physical wall pressure ($Psi_p$) and osmotic concentration ($Psi_s$).
Frequently Asked Questions
What is Water Potential (Ψ)? ▼
Water potential ($Psi = Psi_p + Psi_s$) measures the potential energy of water per unit volume relative to pure water at atmospheric pressure (0 bars/MPa). Water always flows passively from higher (less negative) to lower (more negative) potential.
How is Solute Potential (Ψs) calculated? ▼
Solute (osmotic) potential is calculated using the van 't Hoff equation: $Psi_s = -i cdot C cdot R cdot T$, where $i$ is ionization, $C$ is molarity, $R = 0.0831$ L·bar/(mol·K), and $T$ is temperature in Kelvin.
What is Pressure Potential (Ψp)? ▼
Pressure potential ($Psi_p$) is the physical hydrostatic pressure exerted on water. In plant cells, positive pressure potential is called turgor pressure ($> 0$), maintaining plant rigidity.
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