Heat Stress????

[Shimen]

Hey guys so i came home today and unfortunatly found one of my plants terrible thirsty. At a closer inspection i saw this almost bronze discoloration on the leaves closest to the lights. They are brittle and break easy. I watered it and watched the leaves perk back up while i watered the other ones. I also have to mention that some of the really bad leaves are folded upwards and are extremly brittle. So i just wanted to make sure this is heat stress and nothing else. Or maybe it is excessive dryness i dont know. But heres a pic and thanks for any responses. BTW On a good note two of my plants are now showing female preflowers. They are not showing pistles yet but the Tear Drop shape is very very prominate. -Peace

[-mu]

Yup, the upward curling leaf margins is a sure sign. If you add CO2 to the environment, you can get off with higher temperatures. Add a fan.

They can handle dryness alright, so long as it's not prolonged.

-mu

ps. I sometimes hang a thermometer from my lights, at plant-top height.