[Answered ]-Drop-down box in Django admin does not auto-populate with choices

You have the + icon because probably you have not added any records to the Genre Model.
Once you add one, the combo box will contain this record.

But it seems the you already knows what the Genres are going to be so you can just do this:

class AudioTrack(models.Model):
    genre = models.CharField(..., choices = GENRE_CHOICES)

and the combo box will contain the choices you have in the list.

and consider do you choices list like:

GENRE_CHOICES = ((0,'Rock'),(1, 'Jazz'),(2,'Hip Hop'))

and after:

genre = models.PositiveSmallIntegerField(choices = GENRE_CHOICES)