I dont see why this is such a mystery, early on in this thread youve had advice that mostly covers this issue:
Your plants can obviously not keep up with the amount of light youre giving, increasing intensity 4x over night. If a light recieves 4x the light but isnt able to phosynthesize anymore than currently then extra light becomes heat on the leaves. The plants are not able to pick up that slack cause:
- Too much at one time
- They were already pushed towards their limits. You havent dialed in environment for optimal transpiration or metabolism. You can already see this on your before photos, the plants look healthy but they have a somewhat sloppy stance, not really reaching for the light like a plant does when its drinking properly. Have you got notes on watering, how much and how often, between this run and your successful tent run? If you see a difference in how much they drink then thats a hint. If you also have records of how the environment differed between good run and bad run this would help even more.
Factors constraining transpiration and how to fix:
- Low temp and vpd : increase temps a little, adjust rh accordingly if needed. Most people would use +80F as their lower temp limit, rather than 77F as a high cutoff. Is it possible that you successfull tent runs ran higher temps than you are now? Is there any reason you run temps this low, seems like youre running a led grow on HID parameters?
- Co2: as mentioned by prawn, high co2 will close the stomata causing no transpiration: lower co2 to see if the plants stance improves.
- Spectrum: spectrum intensity, i dont know if thats a thing but there are differences between r-spec, vipar and sun light that really have an impact on transpiration, R-spec being the least drink inducing spectrum. If you wanna read up on this you can google "stomata aperture action spectrum". Basic info gleaned: blue opens the stomata, green closes it. Transpiration action spectrum has several peaks, especially somewhere halfway between 400 and 450nm where normal white leds dont have spectral coverage (also peaks in uv territory). So what to take from this and your experience: no probs in sunlight as its absolutely full spectrum, plenty of deeper blues than led, along with massive amount of IR which heats the leaf and helps the plant transpire. Vipar: the balance between blue and green favors blue by far, so again it wont give you probs.
What to do in this case is a bit hard but it would involve adding blue, especially if you can get something deeper than 450nm or even get some uv.
Metabolism: depends on proper amounts of light, co2, water, nutes and heat(some other in this case unimportant factors aswell).
Light,co2 and water, we know its handled.
Heat: worth noting that heat is necesary for both the transpiration and the metabolism. Even if you keep your vpd tight and have good transpiration you can still have too little heat. If you wanna test to see if your probs is more due to no drink or no metabolism you can try putting an agriculture heating pad under a plant and see if it differs from the rest in how it grows. If it improves then you know.
Nutes: i dont think theres enough here to say your nutes are on point or no. If you resolve the above and still have issues its likely to be the case. Most people i see using high intensity leds use synthetic/hydro and most people who go from organic to chems seem to improve their high watt led grow.
Ymmv