Ah that makes sense. Gem is bud.
They actualy don’t just cut off the bud. but also around it. They cut off the bud, the latent buds and the spot where latent buds form. If seen 13+ year old plants off wich none ever trew out a single sucker. Although they where planted close and got heavely pruned.
5BB is average on maturation. I think roughly a week before Paulson 1103. And roughly a week after 3309C. (according to some french and german sources, this might be different for you in itlaly. or for me)
I think i have solaris. Or i a friend has a few (i think 7-8 at ~4/5 years old i think).
My grafts on the photo where off (i would have to dubble check)
Muscat Blue Seedless (did not know there was a seedles sport of this. i have my doubts)
i also have
and some others. Most are just going in the 2e leaf this year. rooted end of spring last year.
Back to your origional post.
I remember reading somewhere that some of the different species of grapes, had different buds and latend buds.
I remember them talking about it in america. That in some grapes if the primary bud freezes, an almost invisible latent bud started growing. And that shoot from that latent bud would not produce fruits (since the flower buds are already contained in the primary bud in the winter. But the latent bud has now flower bud starts in it.)
However they where talking about some species having sort of 3 buds. The primary “large” bud. And then a secondary smaller bud (thats normaly latent) that also has flower buds in the bud. And then even a posibility for those almost invisble latent buds.
So it might be that the variety you grafted has those " large" and “smaller, but not truely latent secondary bud” It would be really intresting to see if both thoose shoots produce flowers. Or if only 1 shoot produces flowers. Or both don’t at all.
“Multiple non dormant buds. Or cytokine overdose waking up dormant bud”
Another explanation could be how you treated them.
I know the profesional company’s usualy plant out there grafts a few weeks before winter, so they have a few buds of growth and than go into winter dormancy. That way the 0 to 1 year old grafts they sell, have multiple growth points and instead of slowly growing 1 long shoot, they grow a few medium long shhoots.
“Part about cytokines / auxines”
From what i understand about plant grow hormones (witch im certainly not an expert on, and i am oversimplifying here)
The thing that triggers a bud to grow is mostly Cytokines (and ofc temp). Those mainly get produced in activly growing tips of the roots. And transport only up (against gravity). They save up in the top of the plant. And a high concentration of Cytokines initiates shoot growth from buds. However that growing shoot also produces auxines. Those auxines inhibit shoot development in buds, and travel down to the roots where they promote root growth.
So in the end. If budds wake up and start forming a shoot, depends on the cytokine concentration. But also the proportion between cytokines and auxines near that bud.
So early spring. almost no auxine near top bud. So a little cytokine is needed to wake it up (together with temperature ofc). However a little later in the spring now the shoot is growing, the shoot produces enough auxine to inhibit the formation of side shoots.
This also “explains” why if you take off the growth tip. You get many usualy smaller side shoots. The cytokines saved up near those buds was counteracted by the auxine. High cytokines + high auxine = no shoots. But after you remove the tip, the auxins lower but the saved up high concentration of cytokines remains. High cytokine low auxine = many shoots. The cytokine then gets spread over those multiple growth points and so does the plant resourches. Hence the many but smaller side growths.
You might have had the temp and envoriment so ideal for rapid rooth growth, that so much cytokine was produced that it could wake up both the normal and dormant bud. (usualy the latent/smaller buds need more cytokines to wake up/grow.)
“damaged primary bud. 2 latent buds”
It could also be, that you damaged the large bud. And now you have 2 latent buds that sprout at the same time.
We could probably more accuratly gues, by finding out the bud growth habits of the wild species the species/hybrid is off. And the fact if 1 or both or neither produce flowers. (no flowers i gues, damage bud + 2 latent buds) (1 flower 1 no flower, i gues cytokine overdose) (both flowers i would gues the larger + smaller but no latent bud)