Another Lycoris question

Kenneth Hixson
Mon, 17 Aug 2009 12:16:51 PDT
> All this discussion suggests that someone should try producing tetraploid 
> longituba, sprengeri, or chinensis 

>  Consequently, interspecific hybrids are very likely.

Actually, past experience has been that fertile parents such as normal
diploid species, are often infertile when converted to tetraploids.
And on the other hand, normally infertile diploid hybrids become fertile
when converted to tetraploids.  It seems to work best to produce the
hybrid, then convert it to a tetraploid if necessary.

I second Adam's comment that colchicine is hazardous, and Oryzalin may
be a better choice.  Neither is a good choice to use in your kitchen.

> And the arithmetic rules you cited, important as they might be in their
> relevant contexts, have nothing to do with what we are talking about 
> Adam, if you would like to take on another assignment in which you could
> strut you arithmetic stuff, then explain to the group why triploid plants
> are less likely to yield successful results when used as the male 
parent in
> crosses.

Since I'm not Adam, I'll suggest the exact opposite.
  1)  Assume that a plant has limited fertility--one gamete in a
thousand, whether male or female, is fertile.

2)  Female flowers normally produce many fewer ovules(gametes)--assume
for this discussion, ten ovules per flower.  To produce one seed would
require fertilizing one hundred flowers with a fertile pollen.

3)  Pollen is usually produced in much larger quantities, so when a
flower is pollinated, fifty or a hundred (or more) grains of pollen may
be available to be applied to the stigma of a flower.  To produce one
fertile seed, only ten flowers of a fertile female might need to be

So, one hundred flowers as a female parent, ten as a male.  Which is
easier if you are the hybridizer?  Pollen is produced in much higher
numbers, so there is simply a greater chance of that one-in-
a-thousand happy event using pollen.  There are other factors--
inhibitors which prevent or greatly slow pollen tube growth, etc,
but the fact remains, pollen is produced in greater amounts than
ovules, and until you have that one fertile gamete, whether male or
female, all the other factors are irrelevant.
I remind you that each plant is unique, and arithmetic is only a guide.

One further thought--it is relatively easy to examine pollen to see if
it is of normal size and appearance, and even, in a few hours, check to
see if it will germinate and produce pollen tubes, given a simple
microscope.  Webcams have even been connected to simple microscopes
("electronic microscopes") so you can view pictures of selected pollen
on your computer monitor, post them to the internet, share them with
anyone interested.  One of the posters to the rose hybridizing group
regularly posts URLs of such pollen pictures.  Examining the female
ovules means destroying the ovary, and terminating any possibility of
producing seed.

In the instance of Lycoris squamigera producing seeds which fail to
germinate, is a classic instance of where embryo rescue is
appropriate.  In Lilium, such seeds can be harvested at about fifty
to sixty days after pollination, which is just over half the normal
ninty day period for seed development.  Harvested pods can even be
stored in the refrigerator for at least ten days without harm if you
are simply too busy to do the embryo rescue at fifty days.  I don't
know anyone who has worked with Lycoris, but the procedures are
probably  just a little different--different number of days, hormone
levels, etc.  If it is important enough, embryo rescue isn't really
hard, though it is more expensive than simply sowing seed.

Alternatively, treating it with a chemical to increase the chromosome
number probably would  yield a fertile plant, but then it would be
a hexaploid (6N) and what would you cross it with?  If it produced
3N gametes, you might cross it with a diploid (1N gamete) to produce
a tetraploid (4N), but this seems to work better on paper than in the
real world.


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