Need someone's opinion on my auto

Hey, still somewhat of a new grower. This is my second go with autoflower plants. The one I am having trouble with is 4 weeks old. It is a 9 week sativa dominant strain. I have only given nutrients two waterings ago at a very small dosage. Fox farms "grow big".
Temps are a steady 22-23 Celsius (72F), humidity around 50%. Have been watering every 5-7 days depending on soil. It has been fine up until the last three days and has slowed its growth. I will attach a couple of pictures. Light is 600 watt MH bulb. About 24 inches away.
I realize I am lacking more info on my set up and plants but I appreciate any advice or info given.
Thanks! Happy growing.

Probably root bound. Plus a little clawing - Dark Green ( nitro ). Autos can be too sensitive with feedings sometimes ... I had to start at 1/8 strength sometimes.

You think root bound? My plants are in 5 gallon buckets. I've ad regular plants grow in this size almost four feet and grow perfectly fine. How could this one become root bound in four weeks in this size bucket?

Sorry couldnt tell size from pics ...

I wondered about nitrogen but tried to find similar pics to compare my girl with. I added a small portion I figured I would be about 1/8 or so but probably still over did it. I did read they are more sensitive to nutes. I will hold out on nutes for the next couple of waterings and see if they turn around. Thanks for your input Buddha

Plants don't show typical nitrogen looking deficiency, I'd give her some Cal.Mag.. Do a foliar spray.