Sunlight is essential for plants, because plants need to rely on sunlight for photosynthesis. We all know that sunlight is a continuous spectrum light source, and plant photosynthesis is mainly carried out within the visible spectrum. With the advancement of science and technology, people gradually produce corresponding standard light sources based on the continuous spectrum characteristics of natural light. According to the growth characteristics of plants, people gradually produce plant light sources that can replace natural light to promote plant photosynthesis. However, the produced duty lights are not necessarily consistent with natural light. So how to evaluate the characteristics of plant light sources? Lumens, lux, and foot candlelight have become outdated indicators for determining the requirements of light for plants. Recently, people have begun to use PAR, PPF, and PPFD methods to measure photosynthetic light illumination applications. According to the various illuminance meters I have used, Grun's spectral illuminance meter GL anchor.gifSpectrolux is more suitable for measuring the effective radiation parameters and photon flux density of plant photosynthesis. Grun's spectral illuminance meter can be used to evaluate the spectral characteristics of plant light sources.

A good plant light is to determine the appropriate light level to promote the rapid and prosperous growth of plants. How to determine the characteristics of plant lights and how to choose a spectrophotometer are key factors. Let's talk about the basic principles of plant photosynthetic active radiation (PAR, PPF, PPFD) with Spectrolux.

The first measurement is photosynthetic photon flux or "PPF", which measures the total amount of light produced by a light source per second. In other words, PPF tells us how many standards a light source emits per second. Technically, PPF measures "photosynthetic photons emitted by the lighting system per second." This measurement is expressed in "micropores per second", although PPF does not tell us how much of the measured light is on the plant or other surface.

The second measurement is PPFD, which measures the light reaching the plant or algae. Photosynthetic Photon Flux Density or "PPFD" is a measurement of the amount of light that actually reaches plants and algae, or, as scientists might say: "the number of photosynthetic photons occurring per second on a given surface." PPFD is a "spot" measurement of a specific location on your plant's canopy, and it is measured in micrograms per square meter per second. This measurement is expressed by scientists and light engineers as: mol/m2/s.

A third measurement is the DLI (Daily Light Integral), which measures the total amount of light delivered to plants per day. Growers can think of the DLI as a daily "dose" to plants, although scientists might say that the DLI is a cumulative measurement of the total number of photons reaching plants and algae over each day of light operation. The DLI measures the number of "moles" of photons per square meter, and is expressed as: mol/m2/d.

The DLI is similar to the total amount of rain during a storm, compared to the rate at which rainfall is falling (which is the PPFD). The most important metric for DLI is determining the overall growth rate of plants and algae. Once you know the preferred DLI for your plant or algae, you can easily set up a lighting system to provide the required amount of light.

There are a huge number of photons or light particles in visible light - so large, in fact, that we can't express it with normal numbers, so we use two common measurements to measure large quantities. The first number, which is called a mole, is equal to something called Avogadro's number, which is 60221415000000000000000000! For a more manageable number, a micromole is one ten-thousandth of a mole.

PPF tells us how many photons are emitted by a light source per second. PPFD tells us how much the fixture distributes the photons over a one-meter target (i.e. your plants and algae) in one second. DLI tells us how many photons are delivered to a one-meter target in one complete photoperiod (i.e. a day).

Every aquarium and lighting system is different, and there are many factors that affect the total amount of light a fixture produces. While lumens are easy to measure, they have no relation to the amount of light delivered to plants and algae. PAR, PPF, PPFD, and DLI are precise and consistent terms and measurements used by scientists, algae researchers, horticulturists, and laboratories. PPF tells us how many photons are produced by a lighting fixture per second, but it does not tell us where those photons land. That is why we need PPF density or PPFD.

Defines Photosynthetic Radiation (PAR), which is not a measurement or metric, like feet, inches or kilograms. PAR defines the type of light required to support photosynthesis in plant life. Photosynthetic Photon Flux (PPF) measures the total amount of light (photons) emitted by a light source per second. PPF tells us how much standard a light source emits. It is measured in microseconds and expressed as: moles/second. Photosynthetic Photon Flux Density (PPFD), measures the amount of light (photons) that reaches a target per second. PPFD is measured in square meters per second over an area of 1 meter and expressed in moles/m2/s. Daylight Integral (DLI) cumulatively measures the total amount of light (photons) that reaches a target during a light operation. DLI is measured in moles/m2/d, which is moles per square meter. Photons are the name physicists give to particles of light. Natural or artificial light can be used to promote photosynthesis of plant life.

The growth rate of organisms is directly affected by light exposure. Ultraviolet light with a wavelength of 300-400nm and near infrared light (far red light) with a wavelength of 700-800nm will affect the biochemical reactions and appearance of organisms. In particular, the light of 400-700nm is closely related to the photosynthesis of plants and algae. The light of this spectrum is called photosynthetically active radiation (PAR).

Please understand:

Using this spectrum (double red peak spectrum), the unit planting cost can be increased by about 70% thc/cbd compared with the past.

The better measurement benchmark for the number of photons in the photosynthetically active light (PAR) range is to measure its photosynthetic photon flux density (PPFD), which is "the number of photons falling on a unit area per unit time in the wavelength range of 400-700nm", and its commonly used units are μmol/(sec㎡) or μE/(sec㎡).

The following figure shows the Spectrolux spectrophotometer from Gurun, which can measure radiation from the sun and other light sources, and measure the energy of wavelengths in the range of 340~780nm, with the measurement value in W/㎡. Its sensor simulates the photosynthetic active function to meet the needs of use. At present, most foreign products also take this as the product design direction to meet the needs of professional users.

Radiance measurement range: 0.03 to 600 w/m2 (convertible to μmol/㎡ or μE/㎡·s or Photon/㎡·s)

Illuminance measurement range: 1 lx to 200.000 lx