In the question of plant lights, what is the most frequently asked question? How many PPFD?
If the planting variety and environmental conditions are not provided, in fact, this problem cannot be accurately answered. Plant planting is the conversion process of light radiant energy. The light radiant energy follows the law of conservation of energy in this conversion process. For a certain variety of plants, the first thing to be determined is The light radiation energy that plants need every day, otherwise, there is no basis for the calculation of a series of parameters.
What is DLI?
DLI（Daily light integral）
Refers to the integral amount of light radiant energy per square meter per day under effective solar radiation (PAR), unit: mol/m2d.
DLI is an important photosynthetic parameter in agricultural planting and is the main parameter of agricultural planting scientific research. It has universal planting guiding significance. Under sunlight, due to the photosynthetic irradiance of sunlight (converted into PPFD) with time and weather The situation is constantly changing. This change will even fluctuate between the compensation point and the saturation point. Therefore, the DLI needs to be calculated according to the integral method. The initial calculation can be calculated by the average PPFD and the effective time (hours).
The calculation formula of DLI is calculated according to the average method under sunlight.
DLI=0.0036*PPFD (Average) * Effective time. Effective time unit: hour.
The measured value and effective time of the PPFD need to be adjusted according to the compensation point and the saturation point. Therefore, the DLI value fluctuates daily and needs to be determined by data regression method.
What is DLA?
DLA（Daily light amount）
Refers to the number of moles of photons generated per square meter of PPFD per day during the photoperiod of the artificial light source, in mol/m2d.
Disclaimer: The DLA parameters are defined by Xu Dong, a research institute for bright and solid light sources, and the source needs to be indicated.
Since the light quantity of the plant lamp is constant under the photoperiod, the calculation formula of DLA:
DLA=0.0036*PPFD*PP Photoperiod (hours)
DLA is calculated based on the combination of plant varieties and planting environment, and the DLA of different plants is different.
DLA is the main parameter of planting plant and greenhouse light-filling planting process. It is the main basis for plant lamp design. DLA can be obtained through experimental data or weighted by DLI. It needs experimental data correction. The following are two plant varieties. DLA values for reference:
Lettuce DLA: 9-11
The difference between DLA and DLI
The calculation formulas of DLA and DLI are similar, the units are the same, but the calculation method is different.
DLA is set for plant species, and DLI is the amount of sunlight in a certain area.
DLA is a determined magnitude, DLI is random, and DLI can only be represented as an average.
DLI can only be used in large fields and greenhouses. It can not be used indoors. DLA has plant properties and can be applied to plants in fields, greenhouses and indoors.
DLA is the main parameter of the planting process for quantitative analysis, and DLI is an auxiliary parameter for qualitative analysis.
The optical radiation parameters of a plant factory can produce uncertain results if not calculated according to DLA.
The DLA determines the energy consumption of light radiation in an artificial environment, from which the planting cost can be calculated.
In the greenhouse, the indoor DLI is smaller than the outdoor DLI. The DLI of the greenhouse is usually smaller than the DLA of many plant varieties. When the indoor DLI is smaller than the DLA, the fill light is needed, and the fill light is DLA-DLI. When the indoor DLI is larger than the DLA, it is not needed. Fill light.
The establishment of DLA parameters scientifically provides a theoretical basis for whether the greenhouse is complementary to light and light. The establishment of the system’s DLA database for artificial environments can provide a basic data system for plant plant applications, which is of great significance.