Optical radiation and the light spectrum

Optical radiation is radiation that obeys the laws of geometric and wave optics. It covers the range of electromagnetic waves from 100nm to 1mm. It is divided into three ranges: ultraviolet, visible light and infrared. The visible range is from 380nm to 760nm.

Spectrum is an image obtained as a result of decomposing non-monochromatic light into components with different wavelengths:

Optical radiation and the light spectrum
Monochromatic chart, radiation power
Monochrome wave - one length
Spectrum chart
Spectrum - combination of monochromatic waves

UV spectrum (100-400nm) – The spectrum of UV light that is not visible to the human eye is outside the PAR range (100nm-400nm). About 10% of sunlight is ultraviolet radiation. Plants, like humans, can be damaged by overexposure to UV light. They are divided into 3 types: UV-A (315-400 nm), UV-B (280-315 nm) and UV-C (100-280 nm).

Blue spectrum (400-500nm) – Blue light is the main factor involved in photosynthesis. The blue light spectrum is largely responsible for improving plant quality – especially in deciduous crops. It promotes the opening of the stomatal apparatus – which allows more CO2 to enter the leaves. Blue light drives the peak absorption of the chlorophyll pigment, which is needed for photosynthesis.

This is essential for seedlings and young plants in the growing phase as they create a healthy root and stem structure – especially important when limiting stem stretching is essential.

Green spectrum (500-600nm) – Much of the green light that shines on the leaves is reflected. Thus, we see the green color of this plant. This would appear to be a waste of energy, but the reflected light is scattered and transferred to the lower leaves on the plant.

Red spectrum (600-700nm) – Red light is the second major factor involved in photosynthesis, but like blue light, it has exceptional results in plant physiology. It is responsible for lengthening the stems, determining the flowering period, budding and contributing to the circadian rhythm of plants.

Far red spectrum – far red – (700-800nm) – light that is not considered part of the PAR range (photosynthetic active radiation). When natural days are short, low-intensity (photoperiod) lighting is often provided to promote flowering of long-day plants. For some long-day plants, flowering is most accelerated when photoperiod lighting contains both red and far red light.

“What counts in plant lighting is the quality of light, i.e. a properly selected spectrum.”

See also!

PAR chart
Why is light so important to plants?

What is necessary for the proper functioning of plants? Is all light good?

Chlorofile, fotosynteza, pożywienie roślin
Chlorophylls and their absorption spectrum

Why are the leaves green? Color perception and how it relates to light absorption.

Oprawy do uprawy roślin, PPF, PPFD
PPF and PPFD - the most important parameters of your lighting

What do plants eat? What do the two most important parameters in plant lighting mean?

Niebieski, czerwony, par, UV, IR,
Supplementation of red and blue light

Red and blue are the colors most absorbed by plants to support photosynthesis.

Suplementacja w szklarni
Light supplementation in the greenhouse.

How to illuminate crops when they already have access to daylight.

DLI - Daily Light Integral

An indicator showing the daily amount of light supplied to plants during the year.

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