DLI important or not?

ChefKimbo said:

Slightly off-topic question, could this in anyway be related to the turgidity changes when the plants learn the light cycle. How some plants(and some don't) droop right before lights off and readjust right before lights on. Some plants don't do this, would that be an indication that DLI has not yet been achieved for that plant?

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Yeah that's really strange. Don't know if it's related.

I monitor a lot of sensor data in my grows and I can see the plants evaporate more around the middle of "day". Even though the temperature and humidity of the intake don't change. When I lengthened the day to 14 hours, this peak evaporation moved a bit later in the day. So they also seem to adjust for the day length.

ChefKimbo said:

Slightly off-topic question, could this in anyway be related to the turgidity changes when the plants learn the light cycle. How some plants(and some don't) droop right before lights off and readjust right before lights on. Some plants don't do this, would that be an indication that DLI has not yet been achieved for that plant?

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I would suspect no!
The position of the leaves is directly influenced by the amount of red light.
Give them more red light and the plant will "pray" stronger. That's what I've observed.
Provide additional IR and the leaves become also larger and leaf stalks comes longer, but you lose internodes because the plants stretch more.
I give 320w white and 46w deep red and my girls pray all day long.
Also IR causes stronger pray when used as a flower trigger. All the leaves are steeply upwards, when the IR-light goes on.
So I would say it has more to do with the proportion of red light, how strongly the girls pray and not with the DLI!

BTW, under my 4000°k + 430nm + 485nm veg-light, max. 650μmol/s my girls pray little or very little in a 18/6h circle.

wietefras said:

But can you explain how you would come to any other answer to my question than answer C?

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Because that's the way Quantum mechanics work, you have either a yes or no. They don't take in the variables such as reflectance or how many of the photons are consumed on their path through the canopy. And surely you've seen enough light testing in a tent or garden that shows there is a wide range PPFD or PAR from directly under the light to the edges. How would this be possible if the same density exits as your statement.