I think u can apply but I am not sure

No, You can't participate in the second round counselling if you did't register in the first round.Second round counselling is the upgradation of your college choices from the previous one you  recieved during your First round counselling. These upgradation is done only when the seat in the colleges of your preference is left empty and the student from the next rank is asked to fill it in.

Since you didn't register for the firs round you have not been assigned any college . The student below your rank would have got that seat .Letting you participate in the second round will make an irregularity and cause a problem . So, they don't allow to help the system work propperly .