Pineapple chunk is the most sativa phenotype and is streching very fast everyday, I pick this sativa phenotype because of the very strong pineapple smell. The small damage to the fan leaves last week due to some cold is now fixed and they are not showing any sign of stress.
@Lou_Grows, You're right. It was heat stress, I was pushing the plants as much as I could with a high light DLI and Co2, got very good fast growth around 28/29'C but started seeing stress up around 31/32'C so had to dial it back to 28/29'C.
I run a perpetual grow, the younger plants loved the higher temps but late flower ones didn't handle it well. In the end I've found that 27/28'C with 50-55% RH and Co2 is the best compromise for all the plants at different stages.