At present, the plants in different countries of the light spectrum parameters of basic in light quantum units, from the point of application, using light quantum unit expression spectrum parameters, more scientific research can also help the plant photosynthesis, at the same time, but also to other environmental control quantity calculation and control, such as CO2 to light qualitative research, has developed from simple photosynthesis to light formation correlation,The light quality of FR part also needs to be designed in the plant light spectrum, and the PPF_PAR method cannot describe the role of FR. Therefore, the use of PPFD description has limitations, and YPFD description is needed.
With the study of plant absorption spectra, the LED plant light spectrum design turning to based on the growing environment of light quality and quantity of light matching design, its purpose is not only necessary to conform to the plant growth, photosynthesis, important is to realize the improving the quality of the plant, plant edible taste and balanced as a future plant design in the direction of the light spectrum.
YPF and YPFD
With the in-depth study of plant physiology, the wavelength domain of PAR has been limited, especially for LED light source, so the parameters YPF and YPFD are introduced.
YieldPhotonFlux YPF(YieldPhotonFlux)
The number of micromoles (umol/s) of photons emitted per second over a range of wavelengths 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.
The difference between YPF and PPF is that YPF has a larger wavelength range.
YieldPhotonFluxDensity 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 quality and quantity of LED plants.
For monochrome 430-660nm LED light source, YPF=PPF, other spectra PPF<= YPF.
For YPFD concept, the present paper, there are three kinds of views is a YPFD just said in its photosynthetic photon flux density in the range of the wavelength domain, one is in its wavelength domain through the plant relative quantum efficiency curve (RQE) revised photosynthetic photon flux density, and a viewpoint is YPFD said plants absorb the photon flux.
Obviously, the third view is wrong. If the number of photons absorbed is known in advance, the light spectrum technology of plants has been nearly perfect. However, the current situation is that we do not know the photosynthetic spectrum and the weight of absorption bands.In addition, the basic concept of YPFD and PPFD is the preset value of planting process and the guarantee of light radiation energy.
The second view has the following problems:
1)RQE has limitations. Moakley's RQE was based on the study of plant leaves rather than the overall study of plant canopy.
2)RQE does not form the standard adopted by countries,
3) There are also academic disputes over the weight of plant photosynthetic efficiency in blue light or red light.
4) The practical application effect of RQE weighted spectrum is not obvious.
5) THE RQE curve is still under study, or it may be replaced by a new curve of plant photosynthetic efficiency.
6) LED light source parameters modified by RQE are prone to confusion in data evaluation of various research topics.
7)PAR has limitations in the expression of 365-400nm and 700-780nm, which requires dimension (YPFD) that can cover these bands.
Therefore, we believe that YPFD parameter is the photosynthetic photon flux density that can produce photosynthesis in a wider band.
Light quantum energy efficiency QE
In the wavelength range of 400-700nm, the conversion efficiency of unit electric energy to light quantum is expressed by PPF/W, and the photon energy efficiency QE describes the conversion ability of light source to light quantum.
Calculation formula of photon energy efficiency: QE=PPF/W Unit: umol/J (W: power consumed by light source).
QE is a parameter related to spectral morphology, the higher the value of this parameter, the greater the PPFD value, the same PPFD value indicates that the artificial light source is more energy saving, QE value has the problem of high green light content and efficiency distortion. For LED light source, it is based on the comparison of the same light quality.
QE parameter is the original parameter of spectral design, QE is the parameter related to spectral measurement technology, inaccurate measurement of spectral parameters, QE value distortion, QE value distortion will lead to a very large error in spectral design results.
Currently, the QE of agricultural sodium lamp is up to 2.2, and that of LED light source is up to 2.1.
LED lamp bead, LED plant lamp, other light source plant lamp, QE must be marked, and must be marked together with the light quality.
Daylight allowance (DLA)
In the problem of plant lamp, what spectrum is the most common question?How many PPFD?
If you do not provide the planting varieties and environmental conditions, it is unable to accurately answer this question, plants are optical radiation can conversion process, optical radiation can follow the law of conservation of energy in the transformation process, for a variety of plants, must first determine the plants need the optical radiation energy every day, otherwise, a series of parameters calculation, there is no basis.
DLA refers to the number of moles of photons produced by artificial light source per PPFD per square meter per day under photoperiod (unit: mol/m2d).
Since the light amount of plant lamp is constant under photoperiod, the formula of DLA is as follows:
DLA PPFD = 0.0036 * * PP.PP- Photoperiod (hour)
DLA is calculated comprehensively according to plant species and planting environment, and DLA of different plants is different.
DLA is the main parameter of the planting process for lighting in plant factories and greenhouses, and is the main basis for the design of plant lamps. DLA can be preliminarily obtained by experimental data or weighted by DLI, which needs to be modified by experimental data.In our planting technology expert system, we provide the radiation energy DLA reasonably required by plants per square meter every day, which is related to the planting cost and planting quality. DLA parameters are developed based on the DLI parameters of solar rays studied by agricultural science and have theoretical basis.
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