The strain is Mega Jackpot.
Yes I believe it's nutrition, I have been growing this strain for a couple years now and this is by far the biggest leafs I've seen. This is my second grow using a nutrient automation system that I designed and built. I think I worked out all the issues with the system on the previous grow so everything is going smooth now. The system monitors the water (I grow in hydro) and adds nutrients twice a day if the levels drop below a desired level, PH is also maintained. So the "soup" is always perfect for the plants and doesn't fluctuate more than 50 PPM (or whatever threshold I set) or .2 PH.
Just bragging a little bit now but this system was so worth all the time invested into developing and testing it. Not only am I seeing positive results in the plants, my lazy ass only needs to check on my plants and adjust things about once a week. During late flower I need to add water every other day but I don't have to adjust anything on those days. On a typical week I spend between 5 and 10 minutes working on my garden the entire week combined. I remember a time when I spent 30 minutes a night in my garden.