- Subject: [IGSROBIN] Hybridizing
- From: "Roth, Barry" <BRoth@BROBECK.COM>
- Date: Fri, 12 Apr 2002 15:46:02 -0700
Thanks, William and Sandy, for the compliments. Brian, glad I could help.
Great information in the posts from Ed and Maria! Sandy asks:
>How do you decide what parents to choose?
That depends on what you wish to accomplish. Normally, you would choose a
parent because it has a character, or characters, you would like to see in
the offspring. You might also want a cultivar to be a parent because it has
been a successful parent in past breeding. (That assumes you have that
information, which is rarely the case until you have been hybridizing for a
As Ed says, it doesn't always work that simply, because of cryptic (i.e.,
unexpressed, recessive) variation in the genome of the parents. This adds
to the fun! My favorite among all the zonal seedlings my ten-year
hybridizing project produced was a pale silvery lavender single flower with
a faint green flush at the throat on opening - a color I have never seen in
any other cultivar. This resulted from the cross of a lavender single with
white center and a double medium pink/salmon blend also with a white center.
A complete surprise. None of my carefully planned crosses ever worked out
>How do you know they have compatible chromosomes?
Ed's and Maria's posts have covered chromosomes of species and major hybrids
in depth. A related question: how do we know whether a particular zonal
cultivar is diploid or tetraploid? Short of directly examining the
chromosomes (an involved process; see
http://www.nmt.edu/ftp/orchids/chrome1.1 ) a few features of the plants give
a clue as to ploidy. Tetraploids tend to have thicker leaf substance; a
more toothed, less scalloped leaf margin; sometimes a "hairier" leaf under
the magnifying glass; thicker stems with more solid stipules; thicker
peduncles; flowers sometimes of "semi-double" form, with a set of
well-formed outer petals and a few rather irregular inner petals scrunched
in the middle (but other tetraploids have well-formed, fully double
flowers). Not all of the features are always there, but with a bit of
experience one can often make a good guess. The "Irene" group and the
"Fiat" group of zonals are tetraploids. Virtually all the colored-leaved
zonals are diploids. In practice, if you found that pollination of one
particular variety by another always failed, you might suspect chromosome
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