What is difference between PAR & PPF&PPFD ?July 17, 2017
Most important metrics for a grow lights
If you have been searching led grow lighting systems for your plants, you have likely been bombarded with a variety of metrics that lighting manufactruers use on their products such as :watt , LUX , PAR , PPF , PPFD
and photon efficiency ... While all of these terms do related to light , but only a few really important to a horticulture lighting system , this is the purpose of this article to define these tems and correct some common misunderstandings and help growers understand how to choose a grow lights .
Plant and people perceive light very different . Humans and many animals use something called photopic vision in well-lit condition to perceive color and light , lumens are a unit of measurement base on a model of human eye sensitivity in well-lit conditions , which is why the models is called the photopic response curve (figure 1 ). As you can see , the photopic response curve is bell shaped and shows how humans are much more sensitive to green light , than blue or red light . LUX and lumens measure the intensity of light for commercial and residential lighting application , but it is not accurate to use lux and lumens to measure a horticulture lighting .
Like human lumens &lux to identify commercial and residential lighting , PAR &PPFD is the most important metric to grow lights .
short for Photosynthetically Active Radiation ,represents the fraction of sunlight with a spectral range from 400 to 700 nm which is plants perceive and sensitive light , the amount and spectral light quality of PAR light are the most important metrics to fucus on .
are the primary instrument used to a quantify the light intensity of grow light system , these sensors work by using an optical filter to create a uniform sensitivity to PAR light and can be sued in combination with a light meter to measure instantaneous lighting intensity.