Light research is the basis of spectrum, the quality of light application requires spectral analysis,
LED Grow Light spectrum is particularly important, manufacturers of
Grow Light spectrum design ability determines its market competitive position,
Led Grow Light spectrum needs to be specially designed according to the planting process and can not be copied.
1. Classification of light applications
Visual application: applied to lighting, the physical unit is based on the optical flux weighted by the spectral radiation power of the average visual effect function of human eyes as the main parameter.
Non-visual applications: animal, plant, medical, microbiological, identification, data transmission and other applications, the physical unit is radiation power or light quantum number.
2. The energy of photons
LED is energy conversion phenomenon, electron and hole compound glows when excess energy, to produce photons, the shorter the wavelength, produce the photon energy is higher, the photon is the smallest unit in the process of light transmission energy, plant photosynthesis is this band energy photon absorption, photosynthesis was conducted in the photon energy packet driver, rather than a general light energy,That's why photosynthesis in plants needs photons to express it.
Photosynthesis is produced by photon flux, and it is a process in which energy-carrying photons decompose CO2 and H2O under the action of enzymes to generate new molecules. However, not all photons absorbed by plants produce the same photosynthesis, so photosynthesis needs to be understood from the perspective of energy transfer and the relationship between photons and plants should be understood by "light meal".
The number of photons of photosynthetically active radiation is measured in two units: photosynthetic photon flux (PPF), whose wavelength ranges from 400 nm to 700nm, and the generated photon flux (YPF), whose wavelength range can be determined according to the photosynthetic response of plants.
3,
Plant Lamp parameters and units
Moles (mol)
When describing the basic unit of substance composition, such as molecule, ion, light quantum, etc., molar quantity is usually expressed as 6.022EXP(23) fundamental particles of substance constitute a basic quantity, and the unit is:A photon mole (mol) contains 6.022EXP(23) photons. Due to the large unit of moles in plant photosynthesis, many parameters are expressed in micromoles.
1 mole = 1,000,000 micromoles.
One micromole (umol) contains 60 trillion photons.
PAR
Photosynthetic Active Radiation
Radiation in the specific wavelength range (400-700nm) used by plants for photosynthesis is called photosynthetically active radiation and is labeled in two different units:
One is expressed by photosynthetic irradiance (W /m2), which is mainly used for the broad study of photosynthesis of sunlight.
The second is expressed by photosynthetic photon flux density PPFD (umol/ M2s), which is mainly used in the study of plant photosynthesis by artificial light source and sunlight.
This method of expressing the radiative capacity of the radiation source in terms of the photon flow per second reaching the plant surface is called the PPF_PAR method.
PAR accounts for about 50% of total solar radiation, and it is important to note that the unit of photosynthetic irradiance does not capture the effect of wavelength.
PPF
Photosynthetic Photon Flux refers to the number of micromoles (umol/s) of photons radiated by artificial light source per second in the wavelength band of 400-700nm.
PPFD
Corresponding to PPF is the number of micromoles radiated by light source per square meter per second (unit: umol/m2s), which is the concept of Density.
PPFD refers to the PPF within one square meter.
PPFD is a physical quantity related to the radiation distance, which is inversely proportional to the square of the irradiation distance.
1PPFD represents 1 micromole of photons per second radiated over a surface of 1 square meter.
How big is 1umol per m2s, which means there are 6 photons in 10 square nanometers.
YPF
Yield Photon Flux
The number of micromoles of photons emitted per second (umol/s) in the wavelength range emitted by an artificial light source.The wavelength is generally considered to be 360-760nm, and for LED light sources, the wavelength range is set to 380-800nm.
YPFD
YieldPhotonFluxDensity
Corresponding to YPF is the number of micromoles of radiation per square meter per second, umol/m2s, which is the concept of density.
YPFD stands for YPF in the area of one square meter.
YPFD is a physical quantity related to the radiation distance, which is inversely proportional to the square of the irradiation distance.
YPFD can more accurately express the light quantity of LED plant lighting.
For red blue spectrum, YPF=PPF, other spectra PPF
The difference between PAR and PPFD is that PAR is a physical concept and PPFD is the unit of this physical concept.
Relationship between PPFD and PPF: PPFD is the basic quantity obtained from the planting process parameters, and PPF is the main parameter of lamp manufacturing.
In order to clearly understand the three concepts of radiation, illumination and plant photosynthesis, we made the following table.
For a light source with the same PPF, the relationship between installation height and PPFD is that the installation height increases and the PPFD decreases at a rate of power 2.
4. Quantitative analysis of parameters between different light sources and lamps
For different artificial light, use the following indicators can compare their spectrum between performance parameters, these parameters can also compare the same light source spectrum parameters under the same spectral form different manufacturers performance, usually, these values, the bigger the better, but the number does not mean that planting of high efficiency and professional assessment requires professional skills.
PPF/ W: indicates the PPF generated per watt of power consumption.
PPFD/ W: Indicates the PPFD generated per watt of power consumption.
YPF/ W: YPF generated per watt of power consumption.
YPFD/ W: YPFD generated per watt of power consumption.
These values are related to the spectral form (light quality). If we divide these values by the price of the plant lamp, we can compare the price of the plant lamp. The validity of these values requires independent professional analysis by a third party.
Generally, the maximum agricultural sodium lamp up to 2.2umol/ W, LED light, 2.1umol/ W.
5, light quality, light quantity, photoperiod
Light quality LQ
LQ (Light Quality) refers to the spectral form within a certain wavelength range, without unit.
Light LI
Light Intensity (LI) refers to the number of photons radiated by a Light quality. It can be expressed in terms of photon flow or photon density, in PPF or PPFD.
Photoperiodic PP
Photoperiod PP (Photo Period) : indicates the total time of turning on the plant light in a natural day, in hour.
6. Daily dose of radiation required by plants (important concept)
Many people love to study plant radiation compensation point and saturation point plant lamp should be used according to how much PPFD, from the scope of the compensation point to the saturation point is larger (as shown in the figure below), in the scope of the choice of plant lamp light measuring tool for randomness, compensation point and saturation point is only qualitative analysis, quantitative process must consider other environmental factors, can't machine understanding.
In general, the compensation point and saturation point only appear in a certain period of time and are not constant, so it is not scientific to set PPFD with the compensation point and saturation point. In our planting process expert system, we give the reasonable amount of radiation required by plants per square meter every day, which is related to planting cost and planting quality.This parameter is based on the planting technology parameter DLI, which has been studied for a long time in agricultural science.
Daylight dose DLA
Daily light amount (DLA) : Refers to the number of moles of photons generated per PPFD per square meter of artificial light under photoperiod per day (unit: mol/m2d).
Since the amount of light from plant lamps is constant under photoperiod, DLA=0.0036*PPFD*PP.PP- Unit of photoperiod: hour.
DLA is the planting process parameter, and the PPFD required by plant planting in plant factories is calculated by DLA.
Disclaimer: DLA parameters are defined by Xu Dong, Haoliang Solid Light Source Institute.
Solar product component DLI
DLI (Daily light integral) refers to the component of photosynthesis per square meter per day under effective solar radiation, in mol/m2d.
DLI in traditional cultivation is an important amount of photosynthetic parameters, is the technical parameters of agricultural scientific research for a long time, has universal guiding significance of planting, in the sun, the sun of photosynthetic irradiance (converted to PPFD) and the weather is changing over time, this change will be span sometimes between compensation point and saturation point, so,DLI needs to be calculated according to the method of integration, and the initial calculation can be calculated with average PPFD and effective time (hours).
DLI calculated according to average method in sunlight, DLI=0.0036*PPFD (average) * effective time.Valid time unit: hour.
In outdoor planting, DLI parameters will be affected by saturation point. In greenhouse, indoor DLI is smaller than outdoor DLI, and the DLI of greenhouse is usually smaller than DLA. The establishment of DLA parameters provides scientific theoretical basis for whether the greenhouse is filled with light and the amount of light, and establishes the DLA database of artificial light systematically.It is of great significance to provide basic data system for plant factory application. Agricultural researchers are expected to participate in this work.
DLA is the main parameter of the planting process for lighting in plant factories and greenhouses, and the main basis for the design of plant lamps. DLA can be preliminarily obtained by experimental data or weighted by DLI, but it needs to be modified by experimental data. The relationship between DLA and DLI is: DLA
The above is the introduction of the parameters of plant light spectrum. It is very important to understand these parameters of plant light clearly for the application and communication of plant light. The standardized use of these parameters can correctly apply plant light and study plant light spectrum.
