1. What is Water Potential?

Water potential (Ψ) is the potential energy of water per unit volume relative to pure water in reference conditions. It measures the tendency of water to move from one area to another due to osmosis, gravity, mechanical pressure, and matrix effects.

2. How Does the Calculator Work?

The calculator uses the water potential equation:

Where:

• \( \Psi \) — Water potential (MPa)
• \( \Psi_s \) — Solute potential (MPa)
• \( \Psi_p \) — Pressure potential (MPa)

Explanation: Water potential is the sum of solute potential (osmotic potential) and pressure potential. Solute potential is always negative, while pressure potential can be positive or negative.

3. Importance of Water Potential

Details: Water potential is crucial in plant physiology as it determines the direction of water movement through the plant. It helps understand water uptake by roots, transpiration, and cell turgor.

4. Using the Calculator

Tips: Enter solute potential (Ψ_s) and pressure potential (Ψ_p) in MPa (megapascals). The calculator will sum these values to give the total water potential.

5. Frequently Asked Questions (FAQ)

Q1: What are typical water potential values in plants?
A: Leaf water potential typically ranges from -0.2 to -3.0 MPa, depending on water availability and plant species.

Q2: How does water potential relate to water movement?
A: Water moves from areas of higher (less negative) water potential to areas of lower (more negative) water potential.

Q3: What factors affect solute potential?
A: Solute potential depends on the concentration of dissolved solutes - more solutes make Ψ_s more negative.

Q4: What is the role of pressure potential?
A: Positive pressure potential (turgor pressure) helps maintain cell rigidity, while negative pressure potential (tension) occurs in xylem during transpiration.

Q5: Can water potential be measured directly?
A: Special instruments like pressure chambers or psychrometers are needed to measure water potential directly.