Importance of Spectrum
Plants contain a number of photosynthetic pigments which harvest photon energy for growth and development. Each of these pigments have different action spectra which are determined by the energy levels required to excite their electrons into higher orbits. Over the last few decades, these specific energy levels have been discovered by isolating each molecule and measuring their responses to different wavelengths of light.
Unfortunately, these pigment absorption charts have caused a lot of confusion, since they seem to indicate that a large portion of the visible spectrum is unused. However, it has been proven by researchers such as Dr. Ichiro Terashima that even green light is effective at stimulating growth. This is possible because of a complex system of leaf optics which traps photons and forces them to bounce around, losing energy in the process. The energy shift, known as Raman Scattering, offers a chance for higher energy photons to be absorbed and utilized. This is the reason high pressure sodium (HPS) lamps are effective in horticulture, even though their spectrum appears to be the opposite of these absorption charts. The majority of HPS photons degrade into the red spectrum to stimulate the secondary peaks of chlorophyll a & b.
However, this does not mean that all wide spectrum profiles are equal. As can be seen by the spectral charts, the vast majority of the photosynthetic pigments respond only to higher energy violet and blue photons (380 – 500 nm). Chlorophyll a, accounting for more than 55% of all these pigments, requires a more narrow range of 380 - 435 nm for it's primary absorption band. Therefore, optimum spectrum efficiency can only be achieved by saturating the 380 - 435 nm band first and allowing the remaining photons to degrade until they are compatible with the absorption points for other pigments ...as well as the secondary absorption points of both chlorophyll a & b.
It is also important that the spectrum is relatively balanced throughout the 460 – 650 nm range, as this provides time for plant photosystems to process the various photon energies ...including the fluorescence of overstimulated chloroplasts. Otherwise, large spikes in this range would make it difficult for the pigments to capture all of the energy before degrading, reducing fixture effectiveness and crop yields.
Our Advanced fixture optimize our spectrum, HYDRALED utilizes high efficiency LEDs that produce violet and blue photons at 405 nm, 420 nm, and 445 nm. Phosphors are also utilized to create a balanced spectrum profile which maximizes plant utilization and yield. Due to this approach, our fixtures offer improve photon uptake maximize the number of usable photons (umols) produced per watt, while also providing a balanced spectrum.