Re: Re: HYB: Freezing Iris Seeds

In a message dated 8/25/01 9:19:54 AM Mountain Daylight Time, 
koekkoek@mtcnet.net writes:

<< Please forgive what may seem to be, depending on how you take them, 
petulant or impertinent or silly or foolish questions from a person who is 
not into or interesting in doing hybridizing, but for the life of me I can't 
understand why one would want to go to the trouble, expense and extra time of 
something like having to use liquid nitrogen to freeze your seeds.  Why do 
this when so many, it seems, have great success without resorting to all 
that?  Why do this when the way seeds are treated in nature certainly doesn't 
involve such procedures?  Why isn't a method good enough or even more 
preferable that imitates as nearly as feasible the natural state of what 
happens when a seed ripens, falls to the ground, and in time, as winter 
comes, gradually gets cold and (if you live far enough north) freezes and 
stays that way for a while, then warms up and begins to grow?  I read of high 
germination rates from several of you who don't resort to such elaborate 
procedures and then wonder why anyone would want to or feel compelled to do 
more.  I don't mean this to be critical or offensive; just trying to 
understand. >>


Natural methods would certainly be preferable if gardeners were willing to 
settle for the species that are naturally suited for their own climates.  

[WARNING:  I'm going to simplify this by using North America as an example -- 
no offense to listmembers living on other continents is intended!] 

Comparing the climatary regions of their native lands with the climatary 
regions of the North America, we could expect:

1.  The diploid species of eastern Europe to thrive in the northeastern 
United States and a narrow strip of southeastern Canada, as far west as the 
Mississippi Valley, roughly as far south as the Mason-Dixon Line.

2.  The diploid species native to northwestern Europe to thrive in coastal 
Oregon, Washington, and British Columbia.

3.  The tetraploid species native to the Mediterranean to thrive in coastal 
California.

4.  The southern oncos to be at home in the desert southwest of the United 
States and parts of Mexico.

5.  The northern oncos and the regelias to acclimate to the high deserts of 
the western United States.

This would leave parts of the United States and most of Canada and Mexico as 
non-iris-growing regions -- and irisarians have not been willing to settle 
for that!

But the good news is that there is some overlap -- especially between the 
environment needed by the diploid species of central and eastern Europe, but 
also between the diploid & tetraploid species that are the ancestors of our 
modern TBs.  There are areas in which two different types can be grown -- 
albeit not optimally -- and thus hybridized to obtain descendants that are 
more tolerant of a wide range of climates.

The catch is that the two ancestral types may have very different germination 
requirements.  Even though their hybrids have great potential to adapt to a 
wider range of conditions, if they can't be germinated they'll never reach 
that potential.  So hybridizers have resorted to a variety of "Enhanced 
Germination" procedures.

With advanced generations, hybridizers have the choice of line-breeding and 
selecting for ease of germination or out-crossing to broaden performance 
potential.  Some do both, in an attempt to stabilize a line.  

In any case, there is no simple answer. In the modern world of iris, natural 
germination and enhanced germination each has its place. 

Sharon McAllister





 


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