Plants must be exposed to a specific spectrum of light, PAR, in order to perform properly during photosynthesis. PAR technique takes into account wavelengths ranging from 400 nm to 700 nm in most cases.
PPFD (Photosynthetic Photon Flux Density) is a measure of the amount of light falling on plants within the PAR range, expressed in mol/sm2mol. In the past, par light measurements in greenhouses were carried out through lux meters.
The amount of light emitted by PPF
PPF (photosynthetically active photons) is defined as „light emitted by the optical system per second“ by the National Science Foundation. PPF is measured in micromoles per second (µMol/S) – one micromole is around 602 quadrillion photons.
Crop light PPF can be used to determine or estimate the number of crop lights that will be required to deliver the requisite light intensity for a crop in a given area using crop lights.
If strawberry growers attempt to sow seeds with a light intensity of 200 mol/sm2 in order to generate winter crops, they will be able to study this issue.
Approximately 40m2 of cultivation area is provided with an 8m ceiling and a stock spacing of 5m.
This region will require a total of 8000 mol of lights to be adequately illuminated.
The situation as it is right now
The photons in the photosynthetic active band are measured and weighted in the same way as the photons in the rest of the spectrum, which means that the entire spectrum is weighted equally (PAR).
More realistic perspective of PPF and PPFD monitoring
When determining light intensity of a lamp, a spectral sensitivity curve (plm/W) can be utilized instead of a power factor (pf) to make the determination. The PPFD unit is measured in micromoles (one micromole equals 62 quadrillion photons) per square meter per second (µmol/m2/s).
The absorption spectrum of chlorophyll is generated and reflected by the internal and external energy transfer mechanisms of the water and the bulb, which are both internal and external energy transfer mechanisms. This spectrum has a strong influence on the shape of this curve.
There is a difference between the photosynthetic activity spectra of Ulva (two cell layers) and higher plants (multiple cell layers).
Currently, this method is not widely used due to substantial differences in plant light absorption capacity, photochemical capacity, and spectrum color, all of which are highly variable.
As a result, this strategy will be extremely tough to implement.
The PPF lamp does not provide any information. As an alternative, you must examine the sensitivity curve of each crop and provide as much light as possible with the available energy to meet the sensitivity curve of the crop in question.
It is also important to note that the PAR values do not include wavelengths over 700 nm, ultraviolet light, or wavelengths below 400 nm, all of which have an impact on the phytochrome Pfr. This is an extremely crucial fact to understand.
PPFD is critical in photosynthetic systems
During photoperiod, the photosynthetic photoperiod density (PPFD) of a plant growth is used to determine how much light (PAR) the plant receives while photosynthesis is occurring.
For plants that are in the photosynthetically active radiation (PAR) zone, the amount of light they get is defined as the number of photosynthetically active photons that are incident on a certain area per second.
What is micromoles? The PPFD unit is measured in micromoles. The unit of measure for PPFD is mol/s/m2 (mol/sec/square meter).
The amount of light that is emitted per second can be used to provide an accurate comparison of crop illumination (PPFD). It is critical to understand how much PPF or led light is produced by the surface lamp in the area that is positioned inside the PAR zone. To accomplish this, take advantage of the light of the lamp scattering qualities as well as its physical location within the project. Even when both plants are lit with the same quantity of light, the variation in light spread does not always result in the same luminous flux density for the plant. With two CoolStack Boost lamps, a 40 square foot strawberry greenhouse may be created.
Flux of photons measurement
The term „yield“ refers to the number of photons that are emitted and may be measured (YPF).
The photons emitted by the plants in the wavelength range of 360 to 760 nm are measured using the YPF (Yield Photon Flux) method, which takes into consideration the plants‘ reactivity to light.
In addition, photons at wavelengths ranging from 400 to 700 nm, as well as photons calculated from the plant sensitivity curve, are measured for each crop.
Once the precise illumination spectrum of the crop has been determined, the photosynthetic photon flux (PPF) value can be changed by applying different weighting factors to the photosynthetic photon flux for each wavelength and color (PPF).
In this case, Yield Photon Flux is the final result of this operation.
As seen by the red line in the graph, the orange-red 610 nm light produces the greatest amount of photosynthesis per photon of energy emitted.
Considering that short-wavelength light has a high amount of energy per photon, it is the long-wavelength light, which corresponds to a wavelength known as red on some worlds, that produces the greatest amount of photosynthesis per unit of energy.
It was necessary to measure each leaf individually over a short period of time in low light conditions to construct the YPF curve.
Integral light (DLI) employed on a daily basis.
The amount of light that plants receive each day is determined by the amount of time that they spend outdoors each day.
The DLI quantifies the number of photons that reach the plants and algae throughout the course of a 24-hour photoperiod.
When the sunshine index (DLI) is determined, the number of photons in the PAR region per square meter per day, referred to as a „mole,“ is stated as the number of moles per square meter per day.
When it comes to greenhouse lighting projects, DLI is an excellent tool to employ when deciding on the most effective lighting approach.
By looking at the photo, you may get an idea of how much light a plant requires each day to thrive.
On a daily basis, the total amount of sunlight received is exactly equal to the total amount of light received from all natural and artificial light sources combined during the day.