In article ,
Bernhard Kuemel wrote:
Hi sbb!

I discovered purple walnuts:

http://bksys.at/bernhard/img/x27/dscn5930.jpg

I'm impressed. Are they well known, or shall I trace their source
(maybe from one of our trees) and give some to ppl to cultivate
them? Can they grow when already opened? How would you best
germinate them?

I asked a friend who works in a lab associated with the walnut
germplasm repository at U of California in Davis. Walnuts are an
important crop in California.

She says that an opened nut won't germinate. She's seen purple walnuts
before -- they have several cultivars at the repository, including
Livermore which is indeed a "vivid red". It's possible to obtain
material for grafting from the repository, but it's a pain if you're
outside the US.

I forgot to ask her the genetics of purple color in walnuts, but my
guess is that you can't count on it breeding true from seeds of a
random seedling or bud sport. If you can identify the tree or branch
that the walnut came from, you could propagate from it.

While these things are pretty and interesting, there's no telling if
they have any commercial potential. My friend told me that they
received a request from a "cooperator" for permission to remove the
purple cultivars from his test block, since he was being penalized by
the processor for the non-standard nuts showing up in his crop. A
cooperator is a farmer who has the walnut repository provide the trees
for a block of new cultivars on his land. He looks after the trees and
gets the crop, and the repository studies their performance under his
conditions.

One the other hand, the red-skinned sport of the Bartlett pear has
become a commercial variety not very long after it was first released,
so you never know what people will buy.