I believe that the practice of pointing the tap root down is related to the other practice of letting the seeds germinate in paper towels too long, until the tap root has attained significant length. I don't recommend this actually- paper towel fine, but I've read people advising others to let the root get 1/4-1/2 inch long, and I beleive that is not good at all!!!
That's why I plant my seeds as soon as the husk splits and the tap root is VISIBLE- the earlier you plant, the less time and energy is wasted by the tap root orienting itself properly.
D9, I'm gonna go put that in your siggy- if you go into your user CP, you look on the left side of the screen, and edit profile, options, signature, etc are in there.
You guys can't PM, but my email is in my signature.