Encouraging seedlings grown from apple pips to flower

[boundtothesoil]

I'm very new this forum and don't know what's been said before, so maybe someone can direct me to an old thread on this subject, if it's a no brainer.

I'm looking for advice on how to encourage apple seedlings (grown from pips) to grow out of their juvenile phase, which I believe can last from 4 years to infinity, and get them to flower.

I have been crossing varieties on a small scale over the last three years (a couple of flowers per cross) and have so far generated a couple of hundred seedlings (see picture). Although I'm pretty patient, if possible, I'd like to speed up their development so that I can (a) see what kind of apples, if any, they produce before I'm composted and (b) maybe use some in backcrossing to parental varieties.

I've read around a bit, scoured the internet, and am aware that 'breaking juvenility' in apples has been the subject of serious scientific research for many decades. The two most practical/promising suggestions I've come across are:-
1) Grow the seedlings as quickly and as tall as possible, and once they have attained 72 internodes (i.e. 72 successive leaves up the main stem) the juvenile phase ends and subsequent growth is adult (from a commercial breeder in France).
2) Take a cutting or bud from the younger wood after one or two years and graft this onto a rootstock such as M26.

Has anyone been successful with either of these?

I've read on good authority that the youngest growth on the seedling comes out of the juvenile phase first. This year I've pruned off any lateral shoots from my seedlings to encourage faster growth of the main stem. However, I'm not sure if I should prune the main/leading shoot back this winter, because, presumably, by doing this I'm removing the youngest part of the stem, which is also the part most likely to be reaching adolescence, so to speak. Also, if I prune, then I'm going to remove a fair few internodes and delay the seedling reaching the magic 72 internodes. On the other hand, if I don't prune the leader back, I might not get any more extension growth on it next year anyway, and fail to reach the magic 72 internodes for years.

You see my problem!

[FB.]

I can think of two approaches.

1.
Prune the seedlings as if they were upright cordons or minarettes, in order to de-vigorate and induce spurs.

2.
Take grafts from the seedlings onto a very dwarf and precocious rootstock such as M27 or M9 which won't need much space and will probably fruit a year or two after grafting. M26 would be OK too, but maybe more vigorous and not as precocious as would be ideal for trial purposes.
This would also allow you to observe the natural behaviour of the seedlings, which would not be the case if you cordon-pruned them.

In late winter these guys often have rootstocks for sale:
Apple tree rootstocks, Apple Tree Specialists

.

[orangepippin]

I was privileged to visit the garden of Hugh Ermen, one of the greatest English apple breeders of recent years. He had hundreds of seedlings on M9, trained as minarettes and planted about 6" apart. That is the quickest way to see which seedlings have promise.

[boundtothesoil]

Thanks for the advice FB and orangepippin. I will prune these seedlings this winter and where possible graft the more substantial prunings onto rootstocks. Unfortunately, I have a reasonable supply of MM106 stock from a new stool bed, but hardly any M26 or more dwarfing stocks. I started stool beds for MM106 and M26 stocks only two years ago, and the MM106 bed has initially been far more productive, although it is early days. My soil is a heavyish, wet clay, often waterlogged (especially this year), and I mainly use MM106, reasoning that at least part of its generally larger root system might have a chance of experiencing a reasonable soil enviroment sopme of the time, plus resist the frequently windy conditions. Also, because of the waterlogging I only grow over grass, not only due to its beneficial effect on soil structure/porosity, but because it encourages shallow root proliferation by the trees.

On the subject of Hugh Ermen, last year I happened to meet the lady who was (then) the head gardener at The Centre for Alternative Technology near Machynlleth. Not only had she compiled a survey of orchards and apple varieties grown in Powys, but she had also worked with Hugh. She e-mailed me a photo of some of his selections planted in his garden. I'm not sure, but I think she mentioned that his breeding collection had been sent to the nurseryman Frank Mathews etc for safe keeping.

[orangepippin]

I think MM106 is possibly more precocious than M26, but I personally favour M27, as you can sometimes get an initial result the year after bud-grafting.

I believe Hugh Ermen worked with the Matthews nursery and they were involved in propagating of several of his best selections, including Scrumptious. It would be nice if there are still some in the pipeline somewhere. He gave me one of his experimental seedling gages, apparently crossed from Cambridge Gage, and I still have it - contradicting my own advice above, I left it as a seedling and it still hasn't done anything except just get bigger and bigger!