Differences between DLA and DLI in the Field of LED Grow Lights

What are the most frequently asked questions about led grow lights ? what is the lighting spectrum provided of this lighting fixture . how much is the PPFD value.

If you don’t provide the specific planting varieties and environmental conditions, it is unable to accurately answer this question. The growth of plants is process of changing lighting energy to chemical energy . in the transformation process, energy follow the law of conservation . For a certain species of plant, what to be sure first is the needed amount of optical radiation energy of the plant everyday. otherwise,there is no basis to calculate all kinds of parameters regarding led grow lights .

what is DLI？

DLI  (daily light integral) is a measure of the aggregate amount of PAR light that a surface receives over the course of a day. It is a very useful metric to determine if a particular location receives sufficient amounts of light for plants to grow well.

DLI , in agriculture ,is an important parameter regarding photosynthesis;also is the main parameters of agricultural scientific research.in terms of planting , it has universal guiding significance .  in the sun,as the photosynthetic irradiance (converted to PPFD) of sunlight  is constantly changing  with time and weather conditions. this change even will fluctuate in the area below the compensation point or above saturation point. therefore, DLI need to count according to the method of integral method. rough value can be calculated using the average PPFD value and effective time (hours).

Generally , under the sunlight ,we calculate the DLI value with averaging method as follow.

DLI   =   0.0036   *   PPFD(avg)   *  effective time (in hours)

What are known by us is that the measure of PPFD and effective time will have a difference with the change of the compensation point and saturation point .  Therefore, the DLI value fluctuates greatly every day, and the data regression method is needed to determine it.

what is DLA?

DLA (daily light amount ) 

Refers to the number of photons per square meter per day generated by PPFD of artificial light source in photoperiod (mol/㎡/d).

Since the light quantity of led grow light  is constant under the photoperiod, the calculation formula of DLA is :

DLA    =    0.0036    *    PPFD    *    PP  (photoperiod, unit : hour ) 

DLA is based on the comprehensive calculation of plant variety and planting environment. different plants have different DLA.

DLA is the main parameter of plant factory , lighting- supplementing greenhouse  and other cultivation patterns and is the main basis for the design of led grow light. DLA can be preliminarily obtained through experimental data or weighted by DLI, which needs to be modified.

The following is the DLA values of two plant varieties for reference:      Lettuce DLA: 9-11     Tomato DLA: 16-20

The difference between DLA and DLI

1) The calculation formula of DLA and DLI is similar and the units are the same, but the calculation amount is selected in different ways.

2) DLA is set for plant species, and DLI is the amount of sunlight in a given area.

3) DLA is a certain quantity value, DLI is random, DLI can only be expressed by the average.

4) DLI can only be used in field outside and greenhouse (without artificial light source). DLA  has a close relation with the species of crops,can be used in field, greenhouse and indoor  growing.

5) DLA is the main parameter of planting process for quantitative analysis, and DLI is the auxiliary parameter for qualitative analysis.

6) If the optical radiation parameters of plant factory are not calculated based on DLA, they will produce uncertain results.

7) DLA can confirm the energy consumption produced by led grow light in artificial environment, from which the planting cost can be calculated.

8) Under natural conditions, indoor DLI is less than outdoor DLI. Generally ,the DLI in greenhouses is less than DLA of many plant varieties. So when indoor DLI is less than DLA, it is necessary to supplement the lacking illumination.while DLI is equal or greater than DLA, there us no need to take measure to supplement lighting.

9) The establishment of DLA parameter scientifically provides the theoretical foundations for the amount of lighting and the lighting time in greenhouse . by this , you can easy to know whether your greenhouse need to supplement lighting and what is the right amount of light you need to provide . it is of great significance to systematically establish of DLA database of artificial environment,which can provide the basic data system of plants factory application.