
What's good homies?
>> Vlad, I'd say it's some early Ca defc. kicking in,...and I see heat/transpiration stress in those up-curled edges too, which may be part of the defc. cause as well,... any combination of high temps, very low/high RH, strong breeze can trigger some stress; proximity to the lights can make for more localized symptoms too, vs all-around roasting! What happens is, the flow of everything from the roots up slows waaaay down if the plant goes into water stress; the stomata close, so leaf cooling goes out the window, and the usual drawing effect from roots up grinds to a near halt,.. even if there's nutes around, if they don't get hoisted upstairs where they're needed! So, mild defc. can often occur when this happens,... it doesn't necessarily mean the pot is dry either, this is about the plant ability to transpire--evaporate, water from the leaves,... Really high RH is included because the water saturation in the air is so high, it doesn't evaporate for shite, so no cooling,...
@Starbreaker knows what I mean!

I spent 3 years in Gainesville getting my masters there at UoF,...mid 90'sF, nearly the same in RH-- I about died! Only thing I miss is the spectacular lightening


,... Gainesville is near that strip running from Tampa to Jacksonville that's the most lightening struck area in the entire Northern hemisphere!

--you bet, I have run for my life a couple times,...