Leaf problem

i have 6 plants in indoor growroom,at south of china. led light, ph 6.2-6.7, temp 25-30,humidity 65-85,every week fertilize,last two week, all plants leaf between bottom and mid become roll,after 1 week all leaf black anf dead, but top of leaf is fine, what is the problem?
Sorry,My english level is not good, hope everybody know whai i'm say,haha
Thanks ^^

That's heat/moisture stress, your humidity is way high for those temps

I agree with rm3 too hot in grow room do you have adiquate air flow and exhaust? How close are your lights to your leaves?

60cm between plants and light

jason wong said:

60cm between plants and light

Click to expand...

You might need to lower your humidity and keep fresh air flow in and exhaust air out

thanks everyone, i improve the grow room right now