nee grower

Why does my leaves curve Why is it that my top leaves are curling This picture is at 5 weeks veg

Ive just started a no till indoor grow and things seem to be going well. I got , blue og , royal gorilla, diesel glue and darkstar all fem photo periods. One of the seedlings have gone a little light green and the lower leaves are just starting to crisp up. Im growing in a 5x5 tent with a mars...