leaf drooping/taco-ing

First time grower, not sure what's wrong. The leaves are drooping by and large, but also one is taco-ing. (See pic.)

Plant is from bagseed. 19 days old from when the seed when into a rapid rooter for sprouting. It was transplanted to a solo cup after 1 week, and then into a 1 gallon fabric pot 4 days ago.
I have a 600w metal halide light, about 24 inches from the top of the plant currently. On an 18/6 schedule in a 3x3 grow tent. Temperature is usually around 70 F, down to 65 F with the lights off. Although the other day, it got as warm as 81 F in the tent.
Soil is Coast of Maine Stonington blend, which the company says is a just add water supersoil. To date I have not added additional nutrients.
I've just watered this morning, which is the first watering since I watered after transplanting. The soil was relatively dry and the pot light, but not bone dry.

More than likely you have annoyed the plant due to transplant shock, your trying to move the plant far too quickly you only want to transplant it once really if you can help it.
It looks to be a heat/humidity problem aswell, do you own a hygrometer (if not I suggest you buy one).
Have you got any fans setup or extractor/intake fans

Heat stress. What is your humidity level? Like dopeleader suggested get a hygrometer.

Thanks for the reply. There's a small fan blowing across the top of the plant, and an inline fan cooling the light. Humidity is generally ranging between 47-58% It's certainly possible my transplanting technique is not up to par. I read pretty extensively various opinions on transplanting and felt the more compelling argument was to keep potting up in small increments rather than go straight to a large pot. In any event, I'll have to go up at least once more, since it's only a gallon pot right now.

The light doesn't feel particularly warm with my hand under it, but I raised it up half a foot this morning. I keep reading that 18 inches is the sweet spot for a 600w hid light, but perhaps the plant is too young for that? I started at 36 inches and had been lowering it.

The bulb is dimmable, I could also go down to 50 or 75% power?

Sure looks like watering stress IME...I agree about slowing down the transplant process, I think they are happier with 2-3 weeks in the solo cups to develop a sturdy root ball, then they can reach into the new soil and still feed the plant. I wonder if yours is struggling with the combination of the pot up and the recent watering?

I think the 600w is fine, and probably around 2-3 feet from it seems ok to me @ 3 weeks or so....

Yeah, I had intended to keep it longer in the solo cup, but roots were coming out the holes. When I transplanted it, it had pretty much filled the cup already.

gwynnapnudd said:

Yeah, I had intended to keep it longer in the solo cup, but roots were coming out the holes. When I transplanted it, it had pretty much filled the cup already.

Click to expand...

You were smart to get it out of there. Seedlings (versus clones) need more root space, as they grow more vigorously than a cloned version.

I'll echo someone else's opinion: Looks over watered. But you can avoid that by using a larger container, earlier.

Transplant stress. When you do a double transplant and stick it under a big 600watter it will stress /droop. Raise the light stop watering/feeding and move the plant to the side until it perks up. Should be ok in a week or so.