I've been running a little experiment, trying to grow chiles under a mix of sunlight and LED lighting: one habanero growing on my windowsill, and another next to it, getting slightly less light but under a set of high-power blue LEDs during the evening and early night. The plant under the LED does seem to be growing slightly faster (I should now switch them to see if the other starts growing faster), but a few days ago I tried lowering the LEDs to fairly close to the plant, and think I may have burned one of the leaves.
You can see it in the photo below. Is that front leaf sunburnt, possibly slightly toasted, or is it some other kind of damage? And what should I do about it - cut it off, or leave it be?