What is the most problematic question in the plant light problem? How much does PPFD?
If you do not provide planting varieties and environmental conditions, in fact, this problem is not accurate answer, plant cultivation is the process of light radiation energy conversion, optical radiation in the conversion process to follow the law of conservation of energy, for a variety of plants, first of all to determine Plants need light energy per day, otherwise, a series of parameters of the calculation there is no basis.
What is DLI?
DLI (Daily light integral) Daylight integral amount
Refers to the amount of light radiant energy per square meter per day in the effective sunlight (PAR), in mol / m2d.
DLI is an important parameter of photosynthesis in agricultural cultivation. It is the main parameter of agricultural planting scientific research. It has universal planting guidance significance. In sunlight, due to the photosynthetic irradiance of sunlight (converted to PPFD) with time and weather The situation is constantly changing, and this change will even fluctuate below the compensation point and above the saturation point. Therefore, the DLI needs to be calculated in terms of the integral method. The initial calculation can be calculated using the average PPFD and the effective time (hours).
The calculation formula for DLI is calculated according to the average method in the sun:
DLI = 0.0036 * PPFD (average) * effective time. Effective time unit: hours.
PPFD measurements and effective time need to be adjusted according to the compensation point and saturation point. So DLI daily fluctuations are relatively large, the need for data regression method to determine.
What is DLA?
DLA (Daily light amount)
Refers to the number of moles of photons produced by PPFD per square meter per day of the artificial light source in photoperiod, in mol / m2d.
Disclaimer: The DLA parameter is defined by the bright solid light source Institute Xu Dong, citing the need to specify the source.
Since the amount of light in the plant light is constant over the photoperiod, the calculation of DLA:
DLA = 0.0036 * PPFD * PP. PP-photoperiod (hours) DLA is based on plant species and planting environment comprehensive calculation, different plants DLA different.
DLA is the main parameter of the planting process of plant and greenhouse. It is the main basis for the design of plant lamp. DLA can be obtained from the experimental data or after DLI is weighted, and the experimental data is needed. The following are the two plant varieties DLA values for reference:
Lettuce DLA: 9-11.
Tomato DLA: 16-20.
The difference between DLA and DLI
DLA and DLI are similar to the calculation formula, the unit is the same, but the calculation of the amount of different methods.
DLA is set for the plant variety, DLI is the radiation of a region of sunlight.
DLA is the determined value, DLI is random, DLI can only be expressed by the average.
DLI can only be used in the field and greenhouse, can not be used indoors, DLA has plant properties, can be applied in the field, greenhouse, indoor plant cultivation.
DLA is the main parameter of the planting process, used for quantitative analysis, DLI is an auxiliary parameter for qualitative analysis.
The plant's optical radiation parameters, if not calculated on the basis of DLA, produce the result of uncertainty.
DLA determines the energy consumption of light radiation in the artificial environment, from which the plant cost can be calculated.
In the greenhouse, the indoor DLI is smaller than the outdoor DLI, the greenhouse DLI is usually smaller than the DLA of many plant species. When the indoor DLI is less than DLA, it needs to fill the light, the light is DLA-DLI, when the indoor DLI is bigger than DLA, Fill light.
DLA parameters of the creation of a scientific basis for the greenhouse to provide light and fill light the size of the theoretical basis. The establishment of a system based on the artificial environment of the DLA database, can provide plant plant application of the basic data system, has a very important significance.
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