1. What is DLI?

The Daily Light Integral (DLI) measures the total amount of photosynthetically active radiation (PAR) delivered to plants over a 24-hour period. It's expressed in moles of photons per square meter per day (mol/m²/d).

2. How Does the Calculator Work?

The calculator uses the DLI formula:

Where:

• \( PPFD \) — Photosynthetic Photon Flux Density (µmol/m²/s)
• \( hours \) — Duration of light exposure per day (hours)
• 3600 — Seconds per hour conversion factor
• 1,000,000 — Conversion from µmol to mol

Explanation: The equation converts instantaneous PPFD measurements into total daily light exposure by accounting for duration.

3. Importance of DLI Calculation

Details: DLI is crucial for optimizing plant growth, managing greenhouse environments, and ensuring proper light levels for different plant species.

4. Using the Calculator

Tips: Enter PPFD in µmol/m²/s and light duration in hours. Both values must be positive numbers (PPFD > 0, hours between 0-24).

5. Frequently Asked Questions (FAQ)

Q1: What is a typical DLI range for plants?
A: Most greenhouse crops require 10-30 mol/m²/d, while shade plants may need 5-10 and high-light plants 30-50+ mol/m²/d.

Q2: How does DLI affect plant growth?
A: Higher DLI generally increases growth rate up to a species-specific saturation point, beyond which photoinhibition may occur.

Q3: When should PPFD be measured?
A: Measure PPFD at plant canopy level during peak light hours for accurate DLI estimation.

Q4: Are there limitations to this calculation?
A: This assumes constant PPFD during the light period. For variable light conditions, integrate multiple measurements.

Q5: How does DLI relate to crop yield?
A: Most crops show a linear yield increase with DLI up to their optimal range, with diminishing returns beyond that point.