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  • From: Ed & Pat Fackler <rocmdw@aye.net>
  • To: nafex@yahoogroups.com
  • Subject: Re: [nafex] Re: chilling hours
  • Date: Tue, 12 Jun 2001 05:39:59 -0400

Greetings folks:

My 2 cents worth on chill requirements of various fruit species.
Some time around 20 years ago when I was stupid enough to believe all these
written facts, I did some playing around with seed germination in an unheated
basement and other situations.
After some few years of various types, based on what I saw at this
constant 55 degree basement situation, the following observations were noted.
1. Chill time does accumulate at this temperature, but the accumulation
is much slower to occur (than the written "fact" stated). Or, the implication
from this was that so-called "hours or time" is coupled or dependant on
relative temperatures during this period.
2. Subsequent growth appeared to be somewhat slower or the seedlings did
not exhibit normal vigor until the 2nd year in a nursery.
3. One fact was substantiated or appeared to be anyway. That was that
no
chill time accumulates at temperatures below 32 degrees or seeds simply are
suspended indefinately. I put some in a freezer with a constant temp. of
zero. I took them out a year later, stratified and most germinated.

Or, to quote the late Dr. Bob Lamb of Cornell, "the more I learn of these
facts, the less sure I am of them".

Ed, So. Indiana
del stubbs wrote:

> I dont know how to figure chilling hours ....we certainly had 4 months
> completely below freezing, much below 0. I'd say an absolute minimum would
> be 3000 hours below freezing and probably a lot more. I'll call around and
> see if there is actually some gov. agency that actually records such info.?
> any idea where to learn the chill req. of manchurian apricot? Mn. Del
>
> >From: "Kieran or Donna" <redherring@tnaccess.com>
>
> >The chilling hour clocks on stone fruits tick only between 34 and 45
> >degrees
> >(anyone want to fine tune my numbers, which are from memory). Your trees
> >might have clicked off some of the time, but then you got them warm. they
> >stopped ticking. They're like apple trees I have heard of in Florida that
> >went dormant, stayed bare a whole summer, and leafed out the following
> >spring. Apricots in general have short chilling requirements, that is why
> >they do so badly for us with our mild southern winters. They're likely to
> >bloom in Febuary here. You may indeed have to chill your trees to get
> >them
> >to come out. Maybe a block of ice wrapped up with the pots would do the
> >job. How many hours in a week? What do apricots generally need? 500-600
> >hours? Do you think you got half that much before you brought them in?
> >Donna in TN
> >
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