I have seen this posted often - what does this refer too?
Correct me if I’m wrong, gentlepeople.
It’s just an easier way of saying “first generation” and “second generation”, etc.
Any time one makes a cross, the first generation of seedlings is called F1, and the seedlings of those F1 plants are called F2 (I think whether they are self-pollinated, crossed with each other, or crossed with something else).
In the classic scenario, two different species are crossed. A species plant is generally genetically stabilized in the sense that all of its self-pollinated seedlings will be quite similar. Crossing two such stabilized roses will result in a relatively uniform F1 population. That is, all of the first generation seedlings should be fairly similar in characteristics. However, the F2 generation will have a lot of variation.
This is what happens if one plants the seeds from a hybrid tomato, for instance. The seed company stabilized two parent lines by self-pollinating them until they came true from seed with very little variation. Then they made a controlled cross of those two stable parents creating a stable F1 hybrid. They sell that seed to you and you get a tomato with good hybrid vigor and a combination of the characteristics of the two parents. If you plant the seeds from that F1 hybrid, however, the genes recombine in all sorts of ways and the F2 seedlings are very variable.
Such stable F1 hybrids rarely occur when working with roses, because most modern roses carry such a mish-mash of genes. Therefore, the F1 and F2 designations are just a convenient way of talking about first and second generation seedlings of any particular cross.
Yes, short answer is first and second generation descendants. F1 stands for Filial 1, the first filial generation.
Here is a pretty good explanation of Mendelian genetics that might give you a foundation:
http://anthro.palomar.edu/mendel/mendel_1.htm
The fundamentals are essentially correct, but I think it fair to say that scientists realize this gets a little more complicated as we learn more.
You are probably hearing us talk of f1 and f2 with regards to recessive traits that in theory will be lost (or rather, not expressed) in the f1 generation, but hopefully might be expressed again in some of the f2’s, if all goes well. This is much like the “white” color in Mendel’s peas, or the green pea (in the case of the illustrated example in the above link) which doesn’t show in the F1 of a pure cross, but shows up again in later crosses.
In it’s simplest form, folks sometimes consider remontancy (ability to bloom over and over again in one season) to be recessive. This is a little bit of an oversimplification of the reality, but it works for the purposes of hypothesizing, or “armchair hybridizing” as I call it. (All of my greatest crosses are hypotheticals.) A second cross might, in theory, be required to overcome a loss of remontancy, and this F2 generation might give the desired results.
…“might” being the operative word here…
Many thanks to all!!!