- Subject: [IGSROBIN] Hybridizing (1)
- From: Ed Olson Moore <H20wrx@AOL.COM>
- Date: Fri, 12 Apr 2002 04:15:01 EDT
Thanks . Great info.
You pick what characteristics you would like to see combined. That's the
beauty of it. Will it always work-no.
All the zonals have the same parentage (Pelargonium zonale, P. inquinans, P.
acetosum ....), so they all have the same basic chromosome number, x=9. A
diploid plant would have 9 chromosomes (n=9) in the reproductive cells and
twice that number (2n=18) in the vegitative cells. When pollination results
in fertilization, the resultant seed then has 18 chromosomes- 9 from each
parent. From reading the literature, apparently most zonals are tetraploid.
Simply put, they still have the same basic chromosome number (x=9), but their
vegitative cells have 4 times (TETRAploid) that number of chromosomes. The
number of chromosomes in the reproductive cells is termed n, so the number of
chromosomes in the vegitative cells is always twice that number, or 2n. In a
tetraploid zonal then, n=18 and 2n=36. Can a diploid and a tetraploid
geranium be crossed? Yes, but you would probably produce a triploid plant,
which would be sterile and therefore of no use for further crossing.
Interestingly, If you were to double the chromosome number on this triploid
plant, your plant would likely be fertile again. It's a lot more complicated
than that, but the basics are not that difficult to understand.
Can you successfully cross a zonal with an ivy geranium. P. peltatum, from
which all ivys descend , is closely allied with the parents of zonals. All
are in section Ciconium and have the same basic chromosome number. The
question "Will they cross" should be changed to "Do you have the time and
patience". Try hundreds of crosses, you may eventually get lucky.
To be continued..