Autoflower issue nitrogen toxicity or under watering?

watering should never be a problem. constitute your substrate properly and follow a good procedure it is impossible for any rational person to over or under water. ~50% of volume should be drainage amendment - perlite, vermiculite etc. watering: 1) saturate entire substrate -- minimum 10% runoff, if it is a soilless medium 2) wait for appropriate dryback and repeat. (at least a 1/3rd weight loss, but early on i'd suggest a more pronounced wet-dry cycle) It really is simple. Overcomplicating it is when people run into issues from watering. Following a feeding schedule is fine to start, but always ajdust based on what the plant does. Stick to those adjustents in future, too. I don't see any leaf symptoms, so not sure why you think there's a toxicity occurring. N-tox would have very dark (overly lush) leaves, glossiness, and progressing bottom-up on the plant, because it is mobile. Plants do look paler under grow lights, but these are fine. i'd flop any leaves up over the rim as opposed to letting them rest on substrate. They will definitely develop some symptoms if resting directly on substrate.