Article: The future of lighting by focusing on DLI and PSS value

To what extent can a grower produce efficiently more? By measuring several aspects on a daily basis and making adjustments when necessary. The knowledge among both growers and researchers is growing, and with it, the certainty and the quality of the harvest are increasing.


Think of recent developments such as lighting according to the DLI (Daily Light Integral) concept instead of the classic fixed hour schedule: it is not sunny every day, but the crops still need an amount of sunlight every day. Based on weather forecasts, the grower only switches on the LED lighting if necessary, and in the summer months the LED can also be switched on, in contrast to HPS, so that the minimum DLI is still achieved on dark days. This ensures stable production all year-round.

But much more is possible with LED lighting. Developments follow one another closely. For example, we know that there is more far red in the sunrise and sunset than around the middle of the day. We see that especially in the dark seasons. This far red causes a crop to stretch, losing its compactness. It is getting weaker. To prevent this, the LED lighting compensates for this by improving the ratio between red and far red. Together with more blue, this ensures that the crop remains firm and compact.
But it is expected to go a step further in the future. An important factor in crop development is phytochrome, the substance in the plant that reacts to light and regulates all kinds of growth processes. The phytochrome photoreceptors can take two forms, the active and the inactive form, and the relationship between these two is important. On the basis of a measured light spectrum, it can be calculated what the phytochrome balance in the plant will be, this is called the PSS value. With that value, it can be estimated how the plant will develop. It may soon be possible for a grower to not only supplement sunlight to achieve that minimum DLI, but also measure the PSS value of the sunlight and bring it to the desired level by adding specific components of LED light.
Science shows more and more connections between the behavior of the plant and the color of the light. At Oreon we follow these developments closely and conduct active research into this together with Wageningen University & Research (WUR). This way we can always ensure that our LED grow lights helps growers to achieve the optimum crop quality all year-round.


Article: The future of lighting by focusing on DLI and PSS value