Introduction to Core Parameters of LED Plant Grow Lights​

Photosynthetic Active Radiation (PAR):
PAR refers to the specific wavelength range (400-700nm) of radiation that plants use for photosynthesis. It can be measured using two units: Photosynthetic Photon Irradiance (PPI) in watts per square meter (W/m2), mainly used in broad studies of photosynthesis with natural sunlight, and Photosynthetic Photon Flux Density (PPFD) in micromoles per square meter per second (μmol/m2s), primarily used in research involving artificial light sources and sunlight on plant photosynthesis. PPFD measures the photon flux reaching the plant’s surface per second and is calculated using the PPF_PAR method. PAR accounts for approximately 50% of the total solar radiation, but it’s important to note that the unit of photosynthetic irradiance does not reflect the influence of different wavelengths.

PPF (Photosynthetic Photon Flux):
PPF refers to the number of photons emitted by an artificial light source within the wavelength range of 400-700nm per second. It is measured in micromoles per second (μmol/s).

PPFD (Photosynthetic Photon Flux Density):
PPFD corresponds to the number of photons emitted by an artificial light source within the wavelength range of 400-700nm per second per square meter. It is measured in micromoles per square meter per second (μmol/m2s), indicating the density of photons. PPFD represents the PPF within a one-square-meter area. PPFD is a physical quantity that is dependent on the distance from the radiation source and inversely proportional to the square of the distance. 1 PPFD represents one micromole of photons irradiating a one-square-meter surface per second. To put it into perspective, 1 μmol/m2s (PPFD) means there are six photons in an area of 10 square nanometers.

YPF (Yield Photon Flux):
Yield Photon Flux refers to the number of photons emitted by an artificial light source within a specified wavelength range per second. Typically, the wavelength range is considered to be 360-760nm, but for LED light sources, it is set as 380-800nm. YPF is measured in micromoles per second (μmol/s).

YPFD (Yield Photon Flux Density):
YPFD corresponds to the number of photons emitted by an artificial light source within a specified wavelength range per second per square meter. It is measured in micromoles per square meter per second (μmol/m2s), indicating the density of photons. YPFD represents the YPF within a one-square-meter area. Similar to PPFD, YPFD is a physical quantity that is dependent on the distance from the radiation source and inversely proportional to the square of the distance. YPFD provides a more accurate representation of the light intensity and quality of LED plant lights.

Relationship between PPFD and PPF:
PPFD is a fundamental quantity derived from cultivation process parameters, while PPF is the main parameter determined by the design of the light fixture.

Note: Please keep in mind that the translation provided is a general interpretation, and specific technical terms may vary in different contexts.

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