Randomblame
Well-Known Member
Well, these are two different effects, both of which have their uses.
Together with other light you can make use of the Emerson effect and will get higher growth rates depending on the total amount of light. Less light strong effect, much light less strong effect. It is a path that mother nature has devised to enable growth in low-light areas.
To date, there are no tests (except in laboratories) that clearly show which wavelengths and how much of them work best. We can only try to minic the sun. 680 and 710nm theoretically have the most powerful effect as these wavelengths do not need to be converted and directly address PS-I and -II.
When red light strikes a leaf it turns phytochrome red on and phytochrome far-red off. If far-red hits a leaf it turns phyR off and phyFR on. In nature, leaves get both so phyR and PhyFR are permanently switched on and off, on and off.
This somehow compensates for the excitation states of the two photosynthetic systems (PS-I + PS-II). Missing far-red so leads to an imbalance to which the plant can adapt only to a certain point.
EoD treatment causes phyFR to be stay on and phyR to stay off. This is a clear signal for the plant to immediately switch off photosyntosis and switch to night mode. If she does not get far-red at the end of the day, she will first "wait" until it gets bright again(maybe its only shade from dark clouds) and switch to night mode after about 2 hours. This 2h are wasted with waiting and if you use EoD treatment you can make use of this 2h.
Let's calculate with 10 weeks of flowering and 14/10h per day. 70x 2h are 140h or 5.83 days, at 1000 μmol/s/m² and 14 hours a day that's around 251Mol more light.
You can use it to shorten the 10 weeks by ~5.83 days if you stay with 12/12h.
All these effects are regulated via phyR and phyFR. While the initiator effect has the same effect on all short-day plants and is not dependent on the daily amount of light, the Emerson effect is dependent on the total amount of light available. With 1000μmol/s/m² the Emerson effect should be relatively small, maybe 1 or 2%, at only 500μMol/s ppfd it should be more 5 or more % maybe. If you use phyFR to extend the daylength by 2h the plants gets 3275Mol instead of 3024Mol in light, that is about 8.3% more light which theoretically can lead to 8.3% more yield.
So I see clear advantages with the inititator effect since we usually do not work with intensities around the 500μmol/s ppfd. But even if the Emerson effect is pretty small there are other beneficial effects from more deep- and far-red and these have probably even more effect.
I'm sure all these mechanisms are somehow connected, how exactly can I not say. But you can easily use all these effects by adding some red and far-red to it or simply using CRI90 or higher. By combining this with EoD treatment you can combine all these effects and maybe get rates of increase of up to 10% at best. Usually white has already red and deep red but less far-red. You could btw just add far-red to make use of all these effects.
For a red, deep- and far-red boost I would use a 1:1:1,5 ratio or maybe even 1:1:2. This depends on how much of these wavelength are already available before you add more of them. But I would not try to minic the nature and use a 55:45 ratio.
In nature, these values vary greatly due to weather conditions. In indoor applications I would not add more than 20% to white light. Too much red for example causes the pistils to dry up sooner and speeds up the ripening; apart from that they look different and can turn orange. Like with all other growing aspects its a balance act and one need to figure out what works best.
I hope that answers your question, bro.
