PPFD (Photosynthetic Photon Flux Density) mengukur jumlah cahaya aktif fotosintetik (400–700 nm) yang diberikan ke permukaan tanaman per detik, dinyatakan dalam mikromol per meter persegi per detik (µmol/m²/s). Ini adalah metrik paling akurat untuk membandingkan intensitas dan efektivitas lampu tumbuh.
Fakta utama
- Measures light in the photosynthetically active radiation (PAR) range: 400–700 nm
- Unit: µmol/m²/s — how many photons hit one square metre of canopy per second
- Leafy greens thrive at 150–250 µmol/m²/s; fruiting crops need 400–800+
- PPFD varies with distance from the light source — measure at canopy height
- More useful than wattage for comparing grow lights across brands and technologies
- Daily light integral (DLI) = PPFD × hours of light — the total daily photon dose