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LED Lights

Posted by unknown on October 22nd, 2012  ⟩  0 comments

Since our new partnership with Philips, we have been learning a lot about the role of light in plant growth.  For the human eye, light is the visible part of electromagnetic radiation. Since most lighting products are developed for human application the intensity of visible light is expressed in lux. Lux is based on the average sensitivity of the human eye. The sensitivity is maximized at green/yellow (555 nm) and declines towards longer (red) and shorter (blue) wavelengths. However, plants have a completely different sensitivity for colors of light. For plant growth, it is important to define light as small light particles, called photons or quantum. The energy content of photons is different depending on wavelength (color of light). For one W of energy, almost twice as many red photons can be produced compared to blue. In addition, plants are most efficient using the red part of the light and less efficient using the green and blue part. So plant growth (Photosynthesis) is not determined by lux or energy, but by the photons from the blue to red (400-700 nm) part of the spectrum.

Photosynthetic Active Radiation (PAR) is the part of electromagnetic radiation in the photosynthesis active area of 400-700 nm. The number of photons in this area is one of the most important factors in photosynthesis.  Light also affects the germination, stretch, rooting, and flowering of plants.  These processes are influenced by light period, light quality, light amount and light direction.  The ability to control these variable using specific wavelengths is a unique advantage of the Philips GreenPower LED modules. Research has demonstrated that the rate of photosynthesis is determined by the amount of photons between 400-700 nm, called “Photosynthetic Photon Flux” (PPF). The higher the PPF value per Watt, the more efficient the light source for plant growth.  Finding a light source providing as many photons in the PAR region (400-700 nm) per Watt (Joules/s) is very important. This is the reason Philips lists the PPF value in micromols per second (µmol/s).

Although the Philips GreenPower LEDs allow controlling for light, there are other variables that can affect the plant-light interaction such as the effects of light source temperature, spectrum light distribution, interaction with chosen cultivation system and climate conditions. Therefore it is imperative to take a total growth system approach.

Category Code: 88221 88241