I’ll try to raise them up but I don’t think it is light stress. I’m basing that off the fact that tops directly under a light show the same symptoms (as severe) as tops off in the corner of the tent. I would expect tops directly under a light (say 850 PPFD) to show worse symptoms than tops in the corner (say 675 PPFD) if light related. It’s all the tops, on all 4 plants.
Also new undergrowth shows similar symptoms - even though not yet reached the top of the canopy.
I was thinking it might be root issues. When Mag is in excess and not balanced with Ca, it can cause a soil to tighten up. That, along with constant moisture from the drip irrigation might cause a lack of oxygen in the soil - or cause compaction making it difficult for roots to travel? This Mag issue is true for clay soils. Not sure how it affects peat based potting mixes.
Trying to get irrigation dialed in still. Have a tensiometer and I’m still learning, but haven’t yet noticed any wilting or drooping that seemed under or over watering related.
The only time I noticed droopiness was 30 minutes before the lights went out when I was rocking 18/6. To me that seems like the intensity and DLI was right on point.
The plants got their fill in 17.5 hours and took the last 30 minutes of the shift off. Sounds like me right before the work day ends. I’ll be hiding in the sh!tter. lol
Intense light close up can reduce stretch, to a point. Once you are past that point you get light burn. You can throw all the nutes and CO2 at it you want and they'll still burn. You're over thinking things. Raise them up and you'll see.