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nafex - Re: [NAFEX] Spring grafting (david.maxwell@dal.ca) [SEC=UNCLASSIFIED]

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  • From: "ADAMSON, Karl" <Karl.Adamson@apvma.gov.au>
  • To: <nafex@lists.ibiblio.org>
  • Subject: Re: [NAFEX] Spring grafting (david.maxwell@dal.ca) [SEC=UNCLASSIFIED]
  • Date: Fri, 9 Apr 2010 09:53:57 +1000

David, My 2 cents are that if the buds have started going anywhere treat
them just like cuttings and they will stay alive for a long time on the
tree. In other words use parafilm to seal them against desiccation and
shade them if you think it will get too warm. The only reason I'd use
more proximal buds is if I was afraid the breaking buds would get burnt
off by the cold.

Now my understanding of the dormancy process in grapes (maybe other
plants too but I've only ever read about it in reference to grapes) is
that the sieve elements get blocked with something called callose and
this seals the stick against desiccation while it is dormant. In spring
the callose gets broken down and the vessels start their normal job of
conducting water. Consequently the sticks become very sensitive to
drying out at this stage.

Buds will use carbohydrates from their immediate proximity when breaking
dormancy, so its good to include as much wood as possible. Having said
this I let the rootstock determine what kind of graft I'll do. If its
not slipping then I'll whip or chip.

Here is a great write-up on cambium activity in trees.

http://arnoldia.arboretum.harvard.edu/pdf/articles/1785.pdf

David.maxwell@dal.ca wrote:
>1) I am not sure I have ever seen any actual evidence of (grafting
green buds)- has anybody got any personal experience to contribute?
>and
>2)More "scientifically", what is the mechanism here? Is it a question
of changes in the cell
>walls of the cambium cells (which thicken in the Fall, as dormancy sets
in, and then start to
>multiply - with thin walls - as growth resumes) or is it rather a
simple question of metabolic
>demands in the scion which has started to grow (ie. broken dormancy),
in particular a
>question of water movement? In the first instance, there is nothing we
can do to modify
>events. But in the second instance, doing things to prevent the scion
from dessicating before
>it gets vascular channels established with the rootstock may be all we
need to do to get a
>good take despite the scion having broken dormancy. Anybody got any
experience to offer?
>
>And, just to gild this lily a bit more, I note on one batch of scions,
in which the terminal buds
>were left in situ, that it is the terminal buds which have broken
dormancy, while the buds
>farther proximal on the stem are not obviously swollen. If I use these
more proximal buds for
>grafting, am I likely to get a better take? (I suspect that what is
happening here is that the
>terminal bud is sending inhibitory chemicals back down, and keeping the
buds below from
>sprouting - a non-temperature-related dormancy process.)
>
>And, finally, might I do better, with my non-dormant scions to chip bud
them, rather than graft
>(whip and tongue), on the principle that the metabolic demands would be
much less?




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  • Re: [NAFEX] Spring grafting (david.maxwell@dal.ca) [SEC=UNCLASSIFIED], ADAMSON, Karl, 04/08/2010

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