How do sacrifice branches affect auxin flow?

I am the kind of person that generally feels that rules are meant to be broken. And one rule I have heard is that you can only have one sacrifice branch at a time, but when ever I ask for a reason to back up the rule I the response is generally muted. And I'll throw in the disclaimer that the behavior is likely to be species dependent.

I do recognize a couple reasons for why you might want to stick with one sacrifice branch at a time. One, if the sacrifice growth really runs, it can "get away from you," and cause too much thickening for your future tree design. By sticking with one, you can focus on that sacrifice growth and you are less likely to let it "get away."

Another reason not to have multiple sacrifice branches might be the complications of auxin flow. If you are trying to promote back budding on say a black pine, you decandle at some point in the growing season and hopefully get some buds further back on the branches. But if you have sacrifice growth, the general guidance is to let the sacrifice growth run so that it can do it's job and thicken. Even with one sacrifice branch, would the proclivity to back bud be lessened by having a sacrifice branch be allowed to lengthen at the apex? And the guidance becomes even more muddled if you have more sacrifice branches (since the guidance generally already says not to have more than one)

I tend to think that if sacrifice growth is good, more sacrifice growth is better, so as long as the design allows for a thickening of a portion of the branch, I like to let many of the branches extend in order to hasten the development of taper. I keep my interior design tighter and then end up with long branches on the outside lengthen, but reduced to a single bud so lessen the shading effect on the interior design, but it often leaves me at a quandary when it comes to encouraging back budding on the interior.

I realize this is a hodgepodge of ideas and questions, but feel free to weigh in on any aspect of sacrificial growth and how it effects the non sacrificial growth, generally or species specific. In particular, your thoughts on hemlock and black-pine, interest me, but also deciduous and tropical.

Hmm, have you checked by doing, to see how the sacrifice branch works?

To date the only tree that I can grow in a bonsai pot [ 1 inch ] deep and thicken a trunk is our local Ficus.
Just allow an extension of 30 to 36 inches and it happens.

In the ground growing stage, I can have up to 6 branches for trunk or branch thickening [ all at the same time ]

For J.B.pines, 30 to 36 inches in a 16 inch x 5 to 6 inch deep pot, 30 to 38 inches will add on 1 inch of trunk
thickness.
I am about to test a colander in the ground for speed of thickening and with 6 branches.

Hopefully others will chime in.
Until.
Khaimraj

Good point. In a bonsai pot, there may not be enough extra energy to provide for one, much less, more than one sacrifice branch.

In my particular case I have a black pine in an anderson flat (large plastic tray with many holes in the bottom in many ways similar to a colander) that I allow to escape into the ground periodically. Until now it hasn't been allowed to escape for longer than a year. I, so far, have only one sacrifice on top, but have another sacrifice picked out that has just started extending this year to develop taper. As of yet I haven't cut off the top sacrifice, but probably will in about two years, perhaps simultaneous with a heavy root pruning depending on how well the roots are distributed. I haven't really decandled yet either although I meant to this growing season, but missed my opportunity. I have found that the sacrifice seems to have kept the inner branches from over developing with a once a year branch selection.

My Hemlock is in a larger training pot, and given ample fertilizer, seems willing to support a fair amount of extra or sacrifice growth (more than just a top sacrifice but sacrificial branch extensions as well).

In both cases I'd like to develop finer ramification on the inside while at the same time hastening taper and thickening with the sacrifice growth. I realize that these are competing priorities and am trying to develop an approach to utilize the best of both worlds.

I do have some ficus too, but they develop so quickly that I don't bother spending too much time thinking of ways to expedite the process. Sacrifice branches can work wonders for them too, but the real challenge there is not letting them "run away" and over thicken, so I heed the advice of sticking to one sacrifice branch at a time.

Khaimraj,
 Unrelated question, but are you still providing artificial dormancy for your black pines in your climate?  Or, have you "naturally" selected ones from seed that were able to thrive in your environment?  I thought I remembered that you had a refrigerator to induce dormancy for some species and thought black pine required dormancy, but could be wrong on both accounts.

Thanks,
David

edit: Also, I hope that your area has been spared from this tropical storm season.

Hiya David,

J.B.pines, require no special treatment on this side of the Tropics.
On the sea shore side of Japan [ zone 10 ] they probably don't get too much real winter.
They do slow or stop growing after Christmas until mid or the end of February.

The seedlings I selected were those that seemed to especially like a zone 13 [ B? ]
and are fast growing.

The fridge is for Hackberrys, Ginkgo and once upon a time a Trident Maple.
Also a lone apple.

Hopefully, you will figure out ground growing [ we tend to get 3 inch diameter trunks in 1 to 3 years,]
and six branches.
It takes a few more years to get refinement of branches, and it's not so long to work on a tree you love.
Wishing you all the success you can get.
Laters.
Khaimraj