1. What is Vapor Pressure Deficit (VPD)?

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 and nutrient uptake.

2. How Does the Calculator Work?

The calculator uses the VPD equation:

Where:

• \( SVP \) — Saturation vapor pressure (kPa)
• \( RH \) — Relative humidity (%)

Explanation: The equation calculates the difference between the actual water vapor pressure and the saturation water vapor pressure at a particular temperature.

3. Importance of VPD Calculation

Details: VPD is critical for optimizing plant growth conditions. It helps growers maintain ideal humidity levels to prevent plant stress, disease, and optimize photosynthesis.

4. Using the Calculator

Tips: Enter saturation vapor pressure in kPa and relative humidity in percentage (0-100%). All values must be valid (SVP > 0, RH between 0-100).

5. Frequently Asked Questions (FAQ)

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

Q2: How does VPD affect plant transpiration?
A: Higher VPD increases transpiration rate, while very low VPD can cause water stress as plants can't transpire effectively.

Q3: What's the relationship between VPD and temperature?
A: Warmer air can hold more moisture, so SVP increases with temperature, affecting VPD calculations.

Q4: Can VPD be too high or too low?
A: Yes, both extremes are problematic. High VPD causes excessive transpiration and stress, while low VPD limits transpiration and nutrient uptake.

Q5: How often should VPD be monitored?
A: In controlled environments, continuous monitoring is ideal as VPD can fluctuate with temperature and humidity changes.