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 key measurement in greenhouse environments as it affects plant transpiration and growth.

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 crucial for managing greenhouse environments as it directly impacts plant transpiration rates, nutrient uptake, and overall plant health. Optimal VPD ranges vary by plant species and growth stage.

4. Using the Calculator

Tips: Enter Saturation Vapor Pressure in kPa and Relative Humidity in percentage (0-100%). Both values must be valid (SVP > 0, RH between 0-100).

5. Frequently Asked Questions (FAQ)

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

Q2: How does temperature affect VPD?
A: Warmer air can hold more moisture, so temperature directly affects SVP and consequently VPD.

Q3: Why is VPD important in greenhouses?
A: Proper VPD management ensures optimal plant transpiration, nutrient uptake, and prevents issues like edema or excessive water stress.

Q4: How often should VPD be monitored?
A: In controlled environments, continuous monitoring is ideal as VPD can fluctuate rapidly with changes in temperature or humidity.

Q5: Can VPD be too high or too low?
A: Yes, both extremes are problematic. High VPD causes excessive transpiration and stress, while low VPD can lead to poor nutrient uptake and fungal issues.