What is the spectral parameter of LED plant light?

1, the application of light classification

Visual applications: Applied to lighting, the physical unit is based on the average human visual acuity function of the spectral radiation power weighted light flux as the main parameter.

Non-visual applications: animal, plant, medical, microbiology, identification, data transmission and other applications, the physical unit is the radiation power or the number of photons.

2, photon energy

LED luminescence is a phenomenon of energy conversion. When electrons and holes are recombined, the extra energy will glow and produce photons. The shorter the wavelength, the higher the energy of generating photons. The photon is the smallest unit in the process of light energy transfer. The absorption of photosynthesis by plants This photon with energy, photosynthesis is driven by photon energy packets, rather than the general role of light energy, which is why photosynthesis of photons need to express the reason.

What is the spectral parameter of LED plant light?

The energy of a single photon at a wavelength of 400 nm and a wavelength of 700 nm is 1.75, which means that the blue light is 1.75 times larger than the red light.

What is the spectral parameter of LED plant light?

Figure: At the same radiant power, the amount of photons produced increases with increasing wavelength.

Photosynthesis is generated by photon flux, which is the process of photons producing energy that produce new molecules after the decomposition of CO2 and H2O under the action of enzymes. However, not all photons absorbed by plants produce the same photosynthesis and need energy transfer Understanding photosynthesis from the perspective of "light meal" to understand the relationship between photons and plants.

The number of photosynthetically active radiation photons uses two units of measurement: photosynthetic photon flux (PPF) in the wavelength range from 400 to 700 nm and photon flux (YPF) in the second, the wavelength range of which can be determined according to the photosynthetic response of the plant Wavelength range.

3, plant lights parameters and units

Molar amount (mol)

In describing the basic units of a substance, such as molecules, ions, photons, etc., it is usually expressed in terms of molar amounts, which constitute a basic amount of 6.022EXP (23) basic particles in moles, The amount of photons in a plant's photosynthesis is also expressed in terms of molar amount. One photon contains 6.022EXP (23) photons. Because of the large units of photosynthesis in plants, many parameters are expressed as micromolar.

1 mol = 1000000 μmol.

One micromole contains 60 billion photons.

PAR

Photosynthetic Active Radiation

Plants in the specific wavelength range of photosynthesis (400-700nm) radiation called photosynthetically active radiation, the labeling unit has two kinds:

First, with photosynthetic irradiance (w / m2), mainly for the general research of photosynthesis of sunlight.

Second, photosynthetic photon flux density PPFD (umol / m2s), mainly for artificial light and sunlight on the photosynthesis of plants.

This method of applying photons per second to the surface of a plant represents the radiation capability of the radiation source, known as the PPF_PAR method.

PAR accounts for about 50% of the total solar radiation. It should be noted that the unit of photosynthetic irradiance can not reflect the influence of wavelength.

PPF

Photosynthetic photon flux (Photosynthetic Photon Flux) refers to the wavelength in the 400-700nm band, the artificial light source radiates photons microseconds per second, the unit umol / s.

PPFD

Photosynthetic Photon Flux Density Corresponds to PPF is the number of micromoles of radiation per square meter of light source per second, unit umol / m2s, is the concept of density.

PPFD is a PPF representing a square meter.

PPFD is a physical quantity related to the radiation distance, inversely proportional to the square of the illumination distance.

1 PPFD means that 1 micromole of photons per second radiates on a 1-square-meter surface.

How large is 1umol / m2s (PPFD)? It means there are 6 photons in 10 square nanometers.

YPF

The resulting photon flux (Yield Photon Flux)

Refers to the artificial light source in the wavelength range, the number of micromoles of photons per second photons, unit umol / s. The band generally considered to be 360-760nm, for LED light source, the wavelength range is set to 380-800nm.

YPFD

The resulting photon flux density (YieldPhotonFluxDensity)

Corresponding to YPF is the number of micromoles radiated per square meter per second, in units of umol / m2s, which is the concept of density.

YPFD is the YPF in the area of ​​one square meter.

YPFD is a physical quantity that is related to the radiation distance, inversely proportional to the square of the distance that the radiation impinges.

YPFD more accurate expression of LED plant light quality of light.

For the red-blue spectrum, YPF = PPF, other spectra PPF <YPF.

The difference between PAR and PPFD, PAR is a physical concept, and PPFD unit of this physical concept.

The relationship between PPFD and PPF: PPFD is a basic quantity derived from the planting process parameters, PPF is the main parameters of the lamp manufacturing.

In order to clearly understand the three concepts of radiation, lighting, and plant photosynthesis, we made the following table.

Artificial light radiation, lighting, photosynthesis of plants these three concepts comparison table:

For the same PPF light source, the relationship between the mounting height and the PPFD is that the mounting height increases and the PPFD decreases at a power of two.

4, quantitative analysis of different light sources and lamps parameters

For different artificial light sources, the following parameters can be used to compare the spectral parameter performance between them. These parameters can also compare the spectral parameter performance of different manufacturers under the same spectral form of the same light source. Generally, the larger the value, the better. However, Large does not mean that the cultivation of high efficiency, the need to have the professional skills of professional assessment.

PPF / w: Represents the PPF produced per watt.

PPFD / w: Represents the PPFD produced per watt.

YPF / w: YPF generated per watt.

YPFD / w: Indicates the YPFD generated per watt.

These values ​​are related to the spectral shape (light quality). Dividing these values ​​by the price of a plant light makes it possible to compare the price of a plant light. The validity of these values ​​requires a third party independent expert analysis to be reliable.

In general, agricultural sodium lamp up to 2.2umol / w, LED light source, the largest 2.1umol / w.

5, light quality, light, light cycle

Light LQ

Light Quality LQ (Light Quality), is a spectral form within a certain wavelength range, no unit.

Light amount LI

Light Intensity (LI) is the number of photons that can be radiated by a light source. It can be expressed in terms of photon flux or photon density in units of PPF (YPF) or PPFD (YPFD).

Light cycle PP

Photoperiod PP (Period), which means the total time when a plant light is on during a natural day, in hours.

6, the amount of radiation the plant needs daily (important concept)

Many people are keen to study compensation points and saturation points for plant radiation to figure out how much PPFD a plant lamp should use, from a compensation point to a larger range of saturation points (as shown in the figure below) The randomness, compensation point and saturation point are only qualitative analysis, the quantification process must consider other environmental factors, not mechanical understanding.

In general, it is not scientific to set the PPFD with the compensation point and the saturation point, as the compensation point and the saturation point occur only for a certain period of time. In our plantation expert system, we give the result that plants per square meter per day Reasonable amount of radiation required, this value is related to planting costs and planting quality, our parameters refer to the long-standing study of agricultural science and planting process parameters DLI, with theoretical basis.

What is the spectral parameter of LED plant light?

DLA

DLA (Daily light amount): refers to the artificial light source in the photoperiod per day per square meter of PPFD generated by the molar number of photons, unit: mol / m2d.

DLA = 0.0036 * PPFD * PP because the amount of light from the plant lamp is constant over the photoperiod. PP-light cycle unit: hours.

The DLA is a planting process parameter, and the PPFD needed for plant planting in a plant factory is calculated using DLA.

Statement: DLA parameters by the bright solid light Institute Xu Dong definition, the reference needs to be specified.

Daylight integral DLI

DLI (Daily light integral): refers to the amount of photosynthesis per square meter per day under effective solar radiation, unit: mol / m2d.

DLI is an important parameter of photosynthesis in traditional planting. It is a technical parameter of long-term agricultural science research. It has the general guiding significance of planting. Under sunlight, DLI is affected by the photosynthetic irradiance of sunlight (converted into PPFD) In the ever-changing world, this change will occur between the compensation point and the saturation point sometimes. Therefore, the DLI needs to be calculated in terms of points. The initial calculation can be calculated using the average PPFD and the effective time (hours).

DLI calculated by the average method in sunlight DLI = 0.0036 * PPFD (average) * Effective time. Effective time unit: hours.

In outdoor planting, the DLI parameters will be affected by the saturation point. In the greenhouse, the indoor DLI is smaller than the outdoor DLI. The DLI in the greenhouse is usually smaller than the DLA and DLA parameters. The scientific provides the greenhouse with light and It is of great significance to establish a DLA database of artificial light sources and provide the basic data system for the application of plant factories. It is hoped that agricultural researchers will participate in this work.

DLA is the main parameter of the planting process of plant plants and greenhouses. It is the main basis of plant lamp design. DLA can be initially obtained through experiment data or weighted by DLI. However, DLA needs the correction of experimental data. The relationship between DLA and DLI is : DLA <DLI, such as DLI 17 for lettuce cultivation, DLA 9-11.

The above is the introduction of the spectral parameters of plant light. Understanding these parameters of plant light is very important for the application and exchange of plant light. Using these parameters in a standardized way, plant light can be correctly applied and the plant light spectrum technology can be studied.www.luxledchina.com