Plant Photobiology

Accurate Measurement of Light is PAR for the Course!

ILT offers a full line of light measurement systems designed to test, quantify and monitor both natural and artificial light sources used in plant growth, photobiology, photomedicine, and UV photobiology studies.

ILT systems cover the full range of optical radiation (UVB, UVA, VIS,& NIR-Far Red) spectrum for measurement of PAR, PPF, PPFD, and RQE with direct readout in µmol/m2/sec (pronounced micro moles per square meter per second). ILT Spectrometers are available to provide complete spectral analysis from UV-NIR in µmol/m2/sec/nm, as well as transmission and reflectance.

The interaction of light and plant growth (photobiology) is a complex science involving various pigments within the plant such as chlorophyll, carotenes and xanthophylls that transmit, reflect or absorb energy from certain wavelengths that are then used to maximize the photosynthesis process.

However, photosynthesis is not the only consideration when producing a plant for profit. Other aspects like shape, biomass, flowering, coloration, taste, smell, root development, yield and medicinal benefits, etc. are often equally important.

It is well known that there is great variation in light spectrum and intensity requirements among and between species, and the desired affects (stem growth, seed germination,leaf growth, fruit bearing, flowering, THC and CBD production, etc).

Photoreceptors for photosynthesis are most efficient in the blue (400-500 nm) and red (600-700 nm) area of the spectrum. Far-red, (700–800 nm) is critical for flowering of many plants. The (500–600 nm) green area is less understood and even though much of this range is reflected, it is considered beneficial for carotenoids and lycopene (for color and photo-protection).

UV (UVB 280-315 nm and UVA 315-400 nm) radiation is important in inducing production of phenolics, anthocyanins (coloration), antioxidants and vitamins that inhibit mold growth.

Thus the full spectrum from about 350–780 nm at a suitable light intensity can be considered beneficial in plant cultivation. A proper ratio between red and blue light complemented with the correct proportions of far-red and green light and small doses of UV are most often the best mix. The key is to understand and supply the correct spectrum and intensity during the appropriate stage of growth that is optimally suited for the task at hand.

ILT offers a wide range of products designed for monitoring, measuring, quantifying and studying the affects of light on plants

International Light Technologies provides a complete range of plant growth radiometers designed through the joint efforts of International Light Technologies and a team of plant physiologists to specifically measure the effect of light on plant growth in the PAR region of the spectrum.

ILT also offers customized Spectrometers and Photosynthetic Photon Flux Density (PPF) sensors to provide a more accurate weighting to match the exact spectrum required for the species or task under test.

Selecting a System

ILT meters come with NIST traceable, ISO 17025 accredited calibrations in units of Watts, Lumens, Watt/cm2, lux and foot-candles as well as full spectrum analysis.

Input optics, including small cosine receptors, integrating spheres, narrow beam adapters and apertures (for testing uniformity) can be added to ILT systems making them the most versatile systems available.

ILT engineers and technical support staff are available to customize systems to the unique requirements of our customers.

Use the table below to identify the system (meter + detector) that meets your specific application.  Use the table to find the spectral range you wish to measure.  The table can be filtered to show our meters by type, (e.g., hand-held), as well as searching on the minimum and maximum spectral range you wish to measure.  The tables can also be sorted to group systems by meter type, spectral range, measurement range, and units.  Click the product link of the system to view it's details.

Need assistance?  Contact us using the form below, or by calling us at 978-818-6180.

* All Radiometers/Photometers/Spectroradiometers are NIST Traceable.
* If units of measure are not shown please contact us (empirical units also available i.e.
fc, fL, nits, lm/ft²). 

Application Common Sources Meter Type Spectral Range Measurement Range Units Product
PLANT GROWTH (PAR, PPFD, RQE) Sun, Solar Simulator, Plant Growth Lamps, Pink Houses, Green Houses, LED Lights Bench-top/Lab 410-770 nm 2e-6 – 1e3 µmol/m²/sec ILT5000, SED033/PAR/W
PLANT GROWTH (PAR, PPFD, RQE) Sun, Solar Simulator, Plant Growth Lamps, Pink Houses, Green Houses, LED Lights Handheld 410-770 nm 6e-5 – 1e3 µmol/m²/sec ILT2400, SED033/PAR/W
Photosynthetic Photon Flux ("PPF") Individual LEDs, Small Lamps, Focus Beam/Spot Spectrometer 350-780 nm Customized Spectrum µmol/sec/nm ILT950 Spectroradiometer
Photosynthetic Photon Flux ("PPF") Individual LEDs, Small Lamps, Focus Beam/Spot Low Profile 350-780 nm Customized Spectrum µmol/sec/nm ILT550V SPECTRORADIOMETER
Photosynthetic Photon Flux ("PPF") Individual LEDs, Small Lamps, Focus Beam/Spot Bench-top/Lab 410-770 nm 1e-9 – 0.5 ILT5000, SED033/PAR/INS125
Photosynthetic Photon Flux ("PPF") Individual LEDs, Small Lamps, Focus Beam/Spot Handheld 410-770 nm 1e-9 – 0.5 µmol/sec ILT2400, SED033/PAR/INS125
Blue Spectrum Sun, Solar Simulator, Plant Growth Lamps, Pink Houses, Green Houses, LED Lights Bench-top/Lab 370-515 nm 1.4e-10 – 0.286 W/cm² ILT5000, SED033/TBLU/W
Red Spectrum Sun, Solar Simulator, Pink Houses, Green Houses, LED Lights Bench-top/Lab 610-730 nm 5.9e-11 – 0.118 W/cm² ILT5000, SED033/TRED/W
Far Red Spectrum Sun, Solar Simulator, Plant Growth Lamps, Pink Houses, Green Houses, LED Lights Bench-top/Lab 710-810 nm 7.7e-11 – 0.15 W/cm² ILT5000, SED033/TFRD/W
PLANT GROWTH (PAR, PPFD, RQE) Sun, Solar Simulator, Plant Growth Lamps Handheld 300-780 nm 0.3 – 1.5e3 umol/m2*s ILT350 Spectroradiometer