as far i read the emmerson effect gives diminishing returns after a certain light level (was it 600ppfd?).
why is this so? Id like to understand more about these photosystems, why eg cant both use FR - does the energy not suffice to carry out the movement fully?
I always wondered why the Cree curve didnt fell sharply at 700... and even more so around 400... so now that we know leaves can utilize light from 300-750nm, and build biomass with it.
UVA or blue should supress the stretch, problem is uv and blue is absorbed easily by the top leaves far red not, that really goes through the leaves.
So basically you need some kind of blue,uv under the canopy also, or, i think as bruce is saying 660nm should work also.
I do it with leaf/foliage management and plant training. If you have such a dense upper canopy then the middle and bottom shoots will stretch anyway - shade avoidance. Regulates internodial length. Actually a good thing - leaves need direct light.
Or you pluck away that pesky leaf, behold how nodial count increases in veg with swazzing. or buds develop under direct light. light drives the local metabolism wherever it falls on a leaf.
The problem is that light in the 300-500nm range will always be absorbed at first contact with matter (see Video above for reference). How much penetration power has light emitted from a 3w diode or a 25w CFL? when it needs to penetrate 60cm, which is half of my tent.
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@FADING-SILHOUETTE, and you can see, what under- & sidelighting can do. On some pics, it also seems evident that the middle there are less dense buds. Only where the side or underlight hit is density.
What you need instead is green light, at best 550nm. It can penetrate leaves better and does reach deeper. It sort of has the same ability like FR, and is sort of forgotten at even the state-of-the-art boards. These say our tests guarantee its the very best spectrum - but isnt this always said?
Canopy top:
Below canopy:
In natural sunlight, there's much more green than in any growlight. they concentrate too much on the 4 absorption peaks of chlorophyl.
Plants recycle leaves that dont get much light after a time. But the suns green spectrum actually penetrates so deep, trees can have many leaves and sometimes only the innermost gets self-pruned.
I dont think you would be able to grow a tree to such a natural healthy form with any kind of growlight. There would be too much going on at the top, and too less in the middle.
Even the loss of lightstrength over distance is irrelevant in nature but of tragic consequences.... the plant gets confused, doesnt know, where it is... responds by wonky form/outlook...green could solve that, esp. in veg. it would stimulate initial shoot tips even if those are blocked directly from a huge fanleave. then there would be more shoots in the same time, more nodes, less individual shooting high colas - and ultimately: more uniform buds!
Go look how healthy CFL T5 plants grow. They got everything plus the best spreaded lightsource - like the blue sky - the sky itself emits 15-30k lux which encompasses a plant with light from all directions.
Leaf color influences temperature from increased light absorption when darker. This has also a huge impact on light penetration. My personal experience is if leaves are green like grass they grow best.
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