"Dan L." wrote in message news:doesnotwork-

I have been looking for a book that describes what these acronym's mean:
C-3, C-4, F-1, F-2, H-1... I have seen these acronym's often on seed
packets and I am curious of the meaning of what these terms are. Know of
any books?


C3, C4 relate to different ways that the plant does photosynthesis. C4 have
some advantages in that they can keep doing photosynthesis better in hot
conditions. Unless you have some background in chemistry the explanation of
how and why is going to be very heavy going.

F1, F2 relate to the breeding of organisms. The "F" stands for fillial, ie
child. So F1 is the first child generation , F2 the second etc. The reason
that seed packets refer to F1 is that if bred in a particular way it may have
the advantage of hybrid vigour. Remember that generally genes come in pairs
and every child gets one of each pair from each parent.

The way the hybrid breeding works is that you keep two strains of breeding
stock pure, that is for the gene that you are interested in each stock has a
matched pair of genes. So for example if a certain gene (call it the Aye
gene) has forms A and a, then stock one would all be AA and stock 2 would all
be aa. When you cross the two stocks the first (and only the first)
generation are all Aa because they must get an A from one parent and an a from
the other. If the Aa combination is advantageous compared with either AA or
aa then you have an F1 that is uniformly Aa and has a hybrid advantage.

Plant merchants love this setup because the only way to get Aa in all the
progeny of a generation is as described above, so you have to either run your
own breeding program or buy new seed every year. The reason is that if you
breed the F1 together to get F2 it will be a mix of AA, Aa and aa, so if what
you want is Aa then on average only half the F2 will have it. The F3 and so
on will all be various mixtures. In summary hybrids cannot be true breeding.

This is just an example relating to one gene (Aye), obviously there are many
in each species.

Contrast this with heritage, open pollinated varieties. These are all AA (or
aa). Now they may not have the same hybrid vigour but this may not matter, in
many cases it doesn't. What they do have is true breeding. So if the parents
are AA the F1 will be AA (because they must get and A from each parent) and so
will F2 etc. So you can save your seed and be confident that as a population
the next generation will be the same as the last for the Aye gene. No
breeding program required, no need to buy new seed every year.

Just an example of how the Gods mock us, the major food crop that has the C4
advantage (corn) also is a poor performer as a true breeder, that is it takes
great benefit from the F1 hybrid strategy.

"Collapse: How Societies Choose to Fail or Succeed". Sounds cool also.
I am an avid reader of science fiction. Why I like science fiction is
they often describe "what if societies" and from these books from:
Robert A. Heinlen, Neal Stephenson and Vernor Vinge. From these books I
have a good idea how societies might succeed or fail, even from an
agricultural point of view.


"Collapse" is a very good series of case studies combined with explanation of
the principles being illustrated. Evan if you don't accept all of his
explanations the case studies are very informative. He shows that there are
many factors that are needed together to produce a robust healthy society and
failures all lack one or more.

Given the rate of failure of the past this can be rather depressing looking at
the future. I find the only way to avoid such depression is firstly, to be
optimistic that by understanding these modes of failure we can avoid them, and
secondly, to try to live accordingly. And before I am accused of being too
bloody holy - remember I said try.

David