Gardening Under The Grow Light
Plant factory: What parameters need to pay attention to for LED light beads for plant light?
1.Color temperature and lumens of LED lights
???The color temperature and lumen of the plant LED lamp beads are seen from the human eye, and the photosynthesis of light by the plant does not look at the color temperature and lumen. It's more about the spectral components.
2.The effect of spectral range on plant physiology
Full spectrum 3030 lamp beads
Discontinuous full spectrum plant fill light 3030 lamp beads
280 ~ 315nm ——> Minimal impact on morphology and physiological processes
315 ~ 400nm ——> less chlorophyll absorption, affect photoperiod effect and prevent stem elongation
400 ~ 520nm (blue) —> The largest absorption ratio of chlorophyll and carotenoids, which has the greatest influence on photosynthesis
520 ~ 610nm (green) —> the absorption rate of pigment is not high
610 ~ 720nm (red) —> low chlorophyll absorption, which has a significant effect on photosynthesis and photoperiod effect
720 ~ 1000nm ——> Low absorption rate, stimulate cell extension, affect flowering and seed germination
＞ 1000nm ——> converted into heat
From the above data, different wavelengths of light have different effects on plant photosynthesis. The light required for plant photosynthesis has a wavelength of about 400 to 720 nm. Light from 400 to 520nm (blue) and 610 to 720nm (red) contribute the most to photosynthesis. 520 ~ 610nm (green) light, the rate of absorption by plant pigments is very low.
The research basis of light is spectrum. The application quality of light requires spectral analysis. The spectrum of LED plant lights is particularly important. The manufacturer's ability to design the spectrum of plant lights determines its market position. The spectrum of LED plant lights needs to be specifically designed according to the planting process. Go for imitation.
The plant factory is a cross-border product. The Good Bright Solid Light Source Research Institute divides the plant factory technology into planting equipment technology and planting process technology. The plant light spectrum technology is an important connection point between planting equipment and planting process. One thing that needs to be clear is the planting process decision. Spectral design, the design and manufacture of plant lights is to ensure that the light quality required by the planting process can achieve the best efficiency. These characteristics of plant lights determine the complexity and diversity of plant spectral design.
The focus of the LED plant light spectrum is because the spectrum of the LED light source can be designed according to the requirements of the planting process. At the same time, the spectrum of the LED light source can be controlled with variable spectrum through dimming technology. The LED light source is currently the only one that can achieve Variable spectrum plant lamp light source. The technology of variable spectrum of plant lamp is mainly for light shape control, which has little effect on energy saving. Ordinary plant lamps can also save energy by adjusting the photoperiod. The application cost of variable spectrum will increase a lot.
The spectral form of the LED light source is shown in the following table:
4. Photon Energy of LED
LED luminescence is a phenomenon of energy conversion. When electrons and holes recombine, the excess energy will emit light and generate photons. The shorter the wavelength, the higher the energy that generates photons. Photons are the smallest unit in the process of light transfer energy, which is absorbed by plant photosynthesis. It is this kind of energetic photon, and photosynthesis is driven by the photon energy packet, instead of the ordinary light energy effect. This is why plant photosynthesis requires photons to express.
5. Parameters and units of plant light spectrum
5.1 Molar (mol)
When describing the basic units of matter, such as molecules, ions, light quanta, etc., it is usually expressed in terms of molar amount. The molar amount is a basic amount composed of the basic particles of 6.022 EXP (23) substances. The unit is: mole (mol), The number of photons in plant photosynthesis is also expressed in terms of moles. One photon mole (mol) contains 6.022 EXP (23) photons. Because the unit of plant photosynthesis is large, many parameters are expressed in micromoles.
1 mole (mol) = 1,000,000 micromoles (umol).
One micromole (umol) contains 60 billion billion photons.
5.2 PAR: Photosynthetic Active Radiation
The radiation of a specific wavelength range (400-700nm) used by plants for photosynthesis is called photosynthetically active radiation. There are two types of labeling units. One is expressed by photosynthetic irradiance (w / m2), which is mainly used for photosynthesis of sunlight. The second is the generalized study of photosynthetic photon flux density PPFD (umol / m2s), which is mainly used to study the photosynthesis of plants by artificial light sources and sunlight. This method uses the photon flux radiated to the plant surface per second to express radiation. The radiation capacity of the source is called the PPF_PAR method. (Note: m2 means square meters)
PAR accounts for about 50% of the total solar radiation. It should be noted that the unit of photosynthetic irradiance does not reflect the effect of wavelength.
5.3 PPF: Photosynthetic Photon Flux
It refers to the micromolar number of photons radiated by sunlight or artificial light sources per second in the wavelength range of 400-700nm, in umol / s.
5.4 PPFD: Photosynthetic Photon Flux Density
Corresponding to PPF is the number of micromolar emitted by the light source per square meter per second, the unit is umol / m2s, which is the concept of density.
PPFD is a PPF in the range of one square meter
PPFD is a physical quantity related to the radiation distance, which is inversely proportional to the square of the irradiation distance.
1 PPFD means that 1 micromole of photons per second radiates on a surface of 1 square meter.
1umol / m2s (PPFD) at the microscopic level means that there are 6 photons in 10 square nanometers.
5.5 YPF: Yield Photon Flux
It refers to the micromolar number of photons emitted per second in the wavelength range emitted by artificial light sources, in umol / s. The wavelength band is generally considered to be 360-760nm. 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.
5.6 YPFD: Yield Photon Flux Density
Corresponding to YPF is the micromolar radiation per square meter per second, the unit umol / m2s, is the concept of density.
YPFD is the YPF in the range of one square meter.
YPFD is a physical quantity related to the distance of the radiation, which is inversely proportional to the square of the distance of the radiation.
YPFD can accurately express the light quantity of LED plant light quality.
For monochromatic red and blue spectra, YPF = PPF, other spectra PPF <YPF.
The difference between PAR and PPFD, PAR is a physical concept, and PPFD is a unit of this physical concept.