Heat, light stress? Or both?


4 week old. Soil grow. Temps can get high around 38 degrees Celsius( taking care of that. Leave ac on in room during hottest part of the day. Brings tent to 28 degrees) Humidity around 60%. Enough water and some nutrients.18/6 Marshydro TS1000 LED 150w, about 50cm above tops. Some plants have curled leaves some don't. Some higher some lower. Seems random. Would think temp stress but others in the tent seem fine. Light burn maybe but like I said some have it some don't. Thoughts?20210408_121707.jpg20210408_121719.jpg20210408_121703.jpg
Looks like heat stress to me to be honest. I had light stress on mine last grow and it never did this. It stunted the growth and started to fade to yellow before I got it straightened out, but never had the leaf curl. I think the best temp is going to be around 20-30 degrees Celsius during the day and 17-20 during the night. Your heat looks a little high. Are they different strains? Some strains handle heat better than others for sure..