Re: HYB: Pollination
- Subject: Re: HYB: Pollination
- From: L* M*
- Date: Wed, 22 May 2002 17:02:43 -0400
Some more wisdom, this time from Sharon McAllister, originally posted
July 8, 2001:
<1. The juices in the stigmatic lip support the growth of pollen
tubes. This
means that it is more difficult for pollen grain
deposited after the initial
group to grow a tube long enough to reach a
waiting ovum because the juices
have already been depleted -- but not impossible.
2. When working with rare flowers or testing ploidy, the
most-experienced
old-timers did use different pollen on each
stigmatic lip. [Please bear in
mind that I made my first crosses in the 1950s so
"old-timer" undoubtedly has
a different meaning for me than for most of our
list-members.] These
experimenters fell into two groups: 1) those who
would be delighted to get
ANY offspring and thus content to denote the type
of pollen parent rather
than the specific cultivar; and 2) those who were
careful to use widely
different pollen parents and thus trusted their
ability to match any
offspring with the right parent.
3. Hybridizers do sometimes make the mistake of crossing onto a
previously-pollinated flower. By retaining
records of both pollen parents,
experienced ones can sometimes match the
offspring with the parent. Others
simply record the pollen parent as "unknown" --
which is NOT the same as a
bee cross. [Some years ago, I accidentally
crossed both a 1/4-bred and a 3/4
bred onto a 1/2-bred. I got three TYPES of
offspring: one that must have
come from the 1/4-bred, one that must have come
from the 3/4-bred, and one
that could have come from either.]
4. Many hybridizer's protect their crosses by removing the falls [upon
which
bees can land] or bagging the flower. This is
certainly appropriate for
climates in which the stigmatic lip has a
relatively long period of
receptivity. Twice, I set aside a substantial
portion of my garden for
college students who wanted to do some
hybridizing experiments. Although few
pods resulted -- timing is everything -- ALL of
those pods were on stalks
bearing tags. Although there were FAR more
uncrossed and unprotected flowers
that could have been pollinated by bees, none of
them produced pods.
5. Dissection of developing pods has revealed no physical barrier to
the
fertilization of ova in adjoining compartments.
[This is in the archives,
sorry I can't recall the subject line].
Personally, I suspect this happens
only in hospitable climates. I have had many
unbalanced pods develop from
crosses involving all three stigmatic lips, which
I attribute to timing. In
my super-dry climate, with prevailing westerly
winds, the eastermost lip
remains receptive after the westernmost one is
too dry. But the lack of a
physical barrier could certainly explain the
success of those who take
advantage of more favorable conditions to cross
onto only one stigmatic lip.
The proverbial "Bottom Line":
Pod-sibs may indeed have different pollen
parents. Climate and local growing
conditions may promote or discourage this
phenomenon. An individual
hybridizer, taking all of these things into
account, may opt to protect
crosses or to conduct an extended range of
experiments.
There are no easy answers, but it's important
that we evaluate each situation
in light of its specific conditions -- not just
personal experience in our
own gardens.
Sharon McAllister >
reposted by Linda Mann
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