Species DLI - Minimum DLI - Typical DLI - Optimised
In this chart , target DLI numbers are split into three ranges : minimum levels needed for maintenance growth ( indicated in yellow ); typical levels for highest efficiency ( indicated in green ); and optimised levels for maximum growth and yield ( indicated in red ). As you can see there is a high degree of variability between different species when it comes to DLI requirements . Some cultivars can benefit from incredibly intense light levels , but it ’ s important to note plants exposed to these conditions will typically need additional water and fertiliser to accommodate increased photosynthesis . In closed environments the addition of supplemental CO 2 may be necessary .
“ DAILY LIGHT INTEGRAL BECOMES ESPECIALLY IMPORTANT WHEN SUPPLEMENTING SUNLIGHT IN A GREENHOUSE ENVIRONMENT .”
In the Real World
Here ’ s an example of how understanding DLI can help you custom tailor your lighting system to specific crop requirements . Let ’ s assume you ’ re growing a crop that is photoperiod sensitive ; this species needs at least 12 hours of darkness to maintain flowering growth . The target DLI for this particular variety is 34 , which must be achieved within 12 hours so as not to disrupt the reproductive cycle of the plant . The desired PPFD can be found by dividing the DLI requirement by the number of hours , then multiplying by 277.8 . So , for this example 34 / 12 * 277.8 = 787.1 , or just under 800 PPFD . Use a PAR meter and raise or lower your grow light ( or its dimmer ) to achieve the appropriate intensity . Daily light integral becomes especially important when supplementing sunlight in a greenhouse environment . DLI maps that show the average monthly sunlight intensity for specific states or geographic areas are readily available online . Once you know the average sunlight intensity in your area and your specific crop ’ s DLI requirements , it ’ s a simple matter of plugging in the numbers to see how much supplemental lighting you ’ ll need .
HOURS OF LIGHT |
|
6 |
8 |
10 |
12 |
14 |
16 |
18 |
20 |
22 |
24 |
100 |
2.2 |
2.9 |
3.6 |
4.3 |
5.0 |
5.8 |
6.5 |
7.2 |
7.9 |
8.6 |
200 |
4.3 |
5.8 |
7.2 |
8.6 |
10.1 |
11.5 |
13.0 |
14.4 |
15.8 |
17.3 |
300 |
6.5 |
8.6 |
10.8 |
13.0 |
15.1 |
17.3 |
19.4 |
21.6 |
23.8 |
25.9 |
400 |
8.6 |
11.5 |
14.4 |
17.3 |
20.2 |
23.0 |
25.9 |
28.8 |
31.7 |
34.6 |
PPFD
500 10.8 14.4 18.0 21.6 25.2 28.8 32.4 36.0 39.6 43.2 600 13.0 17.3 21.6 25.9 30.2 34.6 38.9 43.2 47.5 51.8
700 |
15.1 |
20.2 |
25.2 |
30.2 |
35.3 |
40.3 |
45.4 |
50.4 |
55.4 |
60.5 |
800 |
17.3 |
23.0 |
28.8 |
34.6 |
40.3 |
46.1 |
51.8 |
57.6 |
63.4 |
69.1 |
900 |
19.4 |
25.9 |
32.4 |
38.9 |
45.4 |
51.8 |
58.3 |
64.8 |
71.3 |
77.8 |
1000 |
21.6 |
28.8 |
36.0 |
43.2 |
50.4 |
57.6 |
64.8 |
72.0 |
79.2 |
86.4 |
The above chart should be used as a reference for comparing PPFD , DLI , and hours of light exposure . The numbers 100-1,000 on the left represent PPFD , while the numbers 6-24 at the top represent hours of light , and the numbers in the centre show the resulting DLI achieved . Utilising DLI calculations will give you more flexibility in the design and implementation of plant lighting systems . Understanding DLI will give you another important tool for optimising plant health and production in outdoor , indoor , and greenhouse environments . Mastering these concepts will take your growing skills to the next level .
50 Maximum Yield