What is PPFD?

What is PPFD?

Photosynthetic Photon Flux Density (PPFD) is used by plants for growth and vital activities. PPFD is a measurement of light and is quantified as the number of photosynthetic active photons that fall on a given surface each second. Light is the major environmental variable which drives photosynthesis in plants.

Plants primarily use wavelengths of light within the visible light range of the electromagnetic spectrum to drive photosynthesis (400 – 700nm). Light which falls within this 400 – 700nm range is called Photosynthetic Active Radiation (PAR). As light intensity (PPFD) increases, photosynthetic rates also increase.

Most plants have three distinct phases of growth: Establishment, Vegetative and Reproductive.

  • Establishment growth occurs after germination or while you are rooting and establishing clones.
  • Vegetative growth occurs when leaves and stems are forming.
  • Reproductive growth occurs as plants transition to produce flowers and fruit.

These three phases require specific PPFD intensities, which increase as the plant develops. The use of LED light sources in indoor horticulture enables a dynamic environment to be created to optimise growth throughout these key growth phases.

During the establishment phase, PPFD intensity needs to remain low as the plant is developing. As the plant moves into the vegetative and reproductive phases, light intensity will be increased in order to provide the plant with more photosynthesises which it will use to develop flowers and subsequent fruit. In order to avoid photo-oxidation (photo-bleaching) the PPFD must be slowly increased to allow the plant time to acclimatise to the increased intensity.

Optimized LEDs that perfectly match the PPFD requirements of each growth phase, drive intense photosynthesis and obtain greater yield, increased crop quality and consistent growth.



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