LIGHTING Terms
Long-Day Plants
Plants that flower when they receive a long day.
Short-Day Plants
Plants that flower when they receive a long night.
Daily Light Integral (DLI)
Daily light integral, The average daily total of sunlight for a given location, usually presented on a monthly basis.The amount of photosynthetically active radiation (PAR) received each day as a function of light intensity and duration. Presented as moles of light per square meter per day (mol/m2/day)
Light intensity
The quantity of light per unit area, typically in units of micromoles per square meter per second (μmol/m2/s).
MLS
Minimum light sum, The minimum amount of DLI needed to produce a minimally acceptable quality crop.
Photoperiod
Period of time each day during which an organism receives illumination; day length.
PAR
Photosynthetically Active Radiation, The region of the light spectrum (400-700 nanometers) used by plants for growth and development. Unlike humans, whose response to light peaks around 550 nm (green-yellow), plants respond most to wavelengths near 400 nm (blue) and 650 nm (red).
PPF
Photosynthetic photon flux, The quantity or intensity of light within the PAR region (400-700 nm) of the light spectrum with units of micromoles per square meter per second (μmol/m2/s).
Light quantity
Also called light intensity, Plant growth is strongly determined by the number of photons that are absorbed in the PAR region.
Day length
The length of day vs night (light vs dark). The time of flowering is often influenced by the photoperiod.
Spectrum
The mix of colors in the light (spectrum) also strongly influences the development of a plant.
Light uniformity When using artificial lighting, uniformity and constant quality of the light spectrum is very important for a constant quality of crop production.
Supplemental Lighting
Light from artificial light sources, including light-emitting diodes (LEDs), high intensity discharge lamps, and incandescent and fluorescent lights, used to supplement the sunlight received by a greenhouse crop.
Sole Source Lighting
The delivery of high light intensities as a substitute for natural light. (No other light source)
LED Lighting
Light emitting diode, Advantages include customizable spectrums, very long life, high energy efficiency and low impact on indoor temperature. LEDs are initially a more expensive option.
Photon
A particle of light
umol (micromoles)
A way to measure the amount of a substance, or in this case the number of photons passing through a target areaf
Joule
One joule is the equivalent of one watt of power radiated or dissipated for one second.
Toplighting
Lighting that is mounted above the crop.
Interlighting
Lighting that is within the plant canopy.
LED Batten lighting
Horticulture LED Battens are designed to facilitate indoor farming by providing a suitable spectrum of light which allows plants to grow indoors efficiently and under ideal conditions. These light are designed to mounted much closer to plants compared to TopLighting.
LED Flowering lamp
These lamps are designed to facilitate greenhouse photoperiod control. Photoperiod control allows growers to manage vegetative growth or rapid flowering throughout the year by extending or shortening day-length. This lamp will help control plants growth so the production is ready at the precise time.
Uniformity
How even the spread of light is across a given area
Efficacy (umol/J)
In essence, the term efficacy is the amount of energy you need to power your lights. For example, Metal Halide lights have an efficacy of 1.25 – 1.46, While many new LEDS have an efficacy of 2.5+. This is measured in Micromoles divided by Joules.
T8 Lamp
(T = Tubular, 8 =eight-eighths of an inch)
T8 lamp is one inch (2.54 cm), in diameter. Both T12 and T8 lamps use the medium bi-pin base, which allows T8 lamps to fit into the same luminaires as T12 lamps of the same length.
Tissue Culture
The cultivation of a plant through the use of a cutting or other plant tissue.
Growth Chambers
Designed to produce environmental conditions (humidity and temperature) that maximize plant growth.
L90, L70, and L80
The point at which the fixture has dimmed to 90%, 80% or 70% of its original output.
IP65 Rated
IP rated as “dust tight” and protected against water projected from a nozzle.
IP66 Rated
IP rated as “dust tight” and protected against heavy seas or powerful jets of water.
IP 67 Rated
IP rated as “dust tight” and protected against immersion.
IP 68 Rated
IP rated as “dust tight” and protected against complete, continuous submersion in water.
UL wet rated
Underwriters Laboratories rated, Only lighting marked “Suitable for Wet Locations” can be used in wet locations. A wet location is a location in which water or other liquids may drip, splash or flow on or against the electrical components of a lighting fixture; UL wet rated means it is safe to use in these environments.
Spectum
A range of light wavelengths usually specified between maximum and minimum values.
80 Degrees
With a highly-focused beam pattern, this distribution option delivers exceptional depth penetration into the plants.
150 Degrees
Offers exceptional uniformity—enabling wider spacing so growers can achieve desired light levels even across the surface of the crop, with fewer modules.
Blue Light (400-499 nm)
– Inhibits stem elongation
– Important for chlorophyll synthesis
– Promotes greening of germinating seedlings
Green Light (500-599 nm)
– Most visually comfortable for human eye
– Best for visual assessment of plant health
Red Light (600-700 nm)
– Speeds up seed germination
– Encourages stem growth
– Essential for flowering and fruit production
Far Red Light (701-750 nm)
– Promotes stem elongation
– Inhibits branching
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