1. What is Vapor Pressure Deficit?

Vapor Pressure Deficit (VPD) is the difference between the amount of moisture in the air and how much moisture the air can hold when it's saturated. It's a crucial measurement for plant growth as it affects transpiration rates.

2. How Does the Calculator Work?

The calculator uses the VPD equation:

Where:

• \( SVP \) — Saturated vapor pressure (kPa)
• \( AVP \) — Actual vapor pressure (kPa)

Explanation: VPD represents the "drying power" of the air, showing the difference between current and maximum possible water vapor in the air.

3. Importance of VPD Calculation

Details: Proper VPD is essential for optimal plant growth. Too low VPD reduces transpiration and nutrient uptake, while too high VPD causes excessive water loss and stress.

4. Using the Calculator

Tips: Enter both SVP and AVP in kPa. These values can be calculated from temperature and relative humidity measurements if needed.

5. Frequently Asked Questions (FAQ)

Q1: What is the ideal VPD range for plants?
A: Typically 0.8-1.2 kPa for most plants, though optimal ranges vary by species and growth stage.

Q2: How does VPD affect plant growth?
A: VPD influences stomatal opening, transpiration rates, and nutrient uptake, directly affecting photosynthesis and growth.

Q3: How can I measure SVP and AVP?
A: SVP can be calculated from temperature, while AVP requires both temperature and relative humidity measurements.

Q4: Why use kPa instead of other units?
A: kPa is the standard SI unit for pressure measurements in scientific contexts.

Q5: Can VPD be negative?
A: No, VPD cannot be negative as AVP cannot exceed SVP by definition.