"The tap root should be up, then it will grow around and down and push the seedling up through the surface. If you plant the tap root down it will first try to go up before going down wasting energy and time. Peace and Pot!"~~Marc Emery When the tap root first comes out it curls around the seed. So, if you plant the seed when the tap root is short, since it's going to curl around the seed, you want to plant it up. Look at the medium length tap roots coming out of the seed in paper towels for example. You can see how they curl around. The root seeks moisture, under lights or not, the deeper the soil, the greater the moisture. This is very much a gravity influenced event. Under lights, i could imagine a struggle between gravity and light. the seedling sprouts without a significant tap root, falls over, dies. Wait til it breaks the surface to add the light...and if it's longer than a cm plant the taproot down.
well first...a seed is polarized...there is the head and the foot. if u plant a seed with the head up...ur root wont curl and will just head straight down. which brings me to the second pt. plants have something called geo-tropism which means that the root heads down and the shoot heads up. according to gravity...by the way...they have tested this in space and the theory is correct. i dont know for sure...but ive grown enough plants to know that if u plant ur seed upright...u are better off than if u plant it upside down. my guess is that u are wasting energy when planting it reversed. emery might have some good vari's but i think he is dead wrong when it comes to this pt. the reason the root twists on a wet plate with paper...is that it cant go down and is looking for other ways to point and grow down...nothing more. personally i germinate all my seeds on a wet plate with paper towel...so i know that i got germination...then i place it right side up just under soil level. using this method and keeping things steril and not too wet...i have virtually 100% post germ sucess.
That's the same way I thought, but in a way it just makes sense. With the old way I had 7 out of 10 seeds sprout. With this way I had 9 out of 10 sprout.
it only makes sense if u think that the tap root has to curl...which i cannot find anything to prove that. the only reason they curl in the wet napkin method is that they cannot go down..and they are curling this way or that way to find a way thru... the root thinks its hitting a rock and gonna twist around till it finds a way. here is an experiment for u to try... figure out which is the head and foot of the seed...then plant it in a soil container of plastic right next to the side...so u can see the root go down. u will see there is no curling... if u want a anatomical reason why u dont want curling... the steel of the root in NO way wants to have any curves in a tap root...its just plain physics. curling is a tropism that is caused by failure of the rootstructure to find its way to geo south. the plant forms auxins on one side of the root to curl it the other way...its a waste of energy and frankly life hates to waste energy...especially in the first part of life.