I have some Pawpaw growing from seeds right now that are a little beyond the stage of your plants.A few have two sets of leaves.
To tell the truth,I'd never heard of that word or practice.From what little I've just read,it sounds like chill hours being applied to promote flowering and fruit later in the year.This is all normal,but the pinching of the leaves is unique.
All I've ever done is start them inside from seed at about 80F until it's warm enough outside or in a greenhouse to support their continued growth.
Who said to do that?Maybe they have something there. Brady

It was Cliff England (where I got the seed) who suggested I could do that. I presume that the purpose of pinching off the leaves is to prevent damage when you put them into the chill temperatures since they won't go through the normal slow process of cooling temperatures and reduced sunlight causing them to drop their leaves normally.

I'm also amazed at how slow the germination and growth seems to be. I'm not sure how large they will be come March. I can always ask Cliff more about it, but I thought I'd see if others on the forums had done it with pawpaw or other trees they started indoors.

I was especially thinking of Alleghany Chinquapins. Since these will germinate immediately in September, I presume they are used to going into dormancy soon after germination.

Has anyone else tried to force dormancy like this?

I've never heard of this process or term. Pawpaws don't grow in just one spring spurt in any case. The paw paw program at Kentucky State University determined a method for getting grafting rootstock in one growing season. Extending the daylight time to 18 hours with bright lights was a big part of it. I think they got 3-foot tall stems by fall the first year. They had the article posted years ago.

Perhaps I should have said "Forcing Dormancy" instead of Vernalizing since that term is generally used for exposure to cold to induce flowering. Flowering isn't really an issue in this case. Cliff was suggesting that removing the leaves and exposing them to 30 days of cold temperatures would give them enough rest to essentially get a second growing season in the first year.

I know KSU has a wealth of information on pawpaw. In fact, I also got some seed from them. I've looked all over their web site but can't find the reference to extending the daylight time. Do you have a link for that? I'm currently using an extended day with all my seedlings but not quite that long.

http://www.pawpaw.kysu.edu/PDF/Layne96.pdf

Page 780, left side, middle.

16 hours, not 18 as I remembered.

Advice referenced to earlier publications.

Outstanding! That was just the information I was looking for. They also talk about defoliating them before introducing them to dormancy temps.