I'm not sure what you mean but if you are talking about a peat pellet or 'gro-dan' or the like, then yes it could make a difference.
Your roots may not have reached the soil yet, which would explain how they could have lots of nutes in the soil, but not be uptaking it into the plant.
Did you see roots before you planted?
It doesn't matter. the rootone and micorrhizae should help in either case if root development is the problem.
Also, your soil looks a bit heavy for rooting seedlings. Roots need oxygen to grow. Next time add some coco fiber for loft, and perlite for drainage.