Broad beans

[12540dumont]

I actually did 2 plantings of favas this year, one in early winter and one in late winter. This is the late winter stand. I have harvested beans for a month from the early winter one. Now, Leo's going to mow it and till it. I'm going to let this one dry down and then harvest the beans. I'm going to need this space for melons!

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[robertb]

Red seeds seem to be a simple dominant; if I plant green and red seeded types together all the seeds come out red. It should be simple to fix in a strain if you want red seeds.

[Joseph Lofthouse]

Jun 4, 2012 11:31:06 GMT -5 robertb said:

Red seeds seem to be a simple dominant; if I plant green and red seeded types together all the seeds come out red. It should be simple to fix in a strain if you want red seeds.

Dominant traits are the most difficult to fix... If you are dealing with recessives, the trait is fixed as soon as you get the desired phenotype from a selfed plant.

But when dealing with a dominant trait, you never really know whether or not the seed is carrying hidden recessive traits, so it takes a very meticulous protocol to fix a dominant trait. It's even harder with a trait like pericarp color which is expressed only in maternal tissue. [Example only: I don't know which layer of the seed imparts color to broad bean seeds.]

[jim]

Difficult? Im not so sure that I would say that.
No, you can't simply bulk all of your seed in the F2 and pick out those that are homozygous dominant...but a generation of single seed descent can identify all those plants that are homozygous dominant. If a plant produces progeny that are segregating, don't save any those plants, but a plant producing only the dominant trait in its progeny should be saved, and bulked with any other families which have shown not to be segregating. For recessives, you can simply select in the F2...but only 25% or so will be recessive (if we are talking about a single gene...)
Seed coat (testa) in legumes is generally maternally derived, thus is the phenotype of the female parent. It follows that you need to select in the F2 and beyond....
Pericarp? That would be more like the fruit, not the seed...I guess you would be talking about the pod itself Joseph? Pod color seems to be simply inherited as well...
Jim

[robertb]

After a few generations of selection, the percentage of genes for green seeds should be vanishingly small.

[jim]

In theory, ok...but look at some numbers. Of all the red seeds in a segregating F2 population, 66.67% will be heterozygous and 33.3% will be homozygyous red.
So, if you were only going to plant 5 red seeds, the chance that all 5 would be homozygous red would be 0.39% If you decide to plant more, the chance would go down even further.
If a true breeding group of red seeded plants is desired, it would be worth a little effort, otherwise, it will be many more than a few generations to select out all the heterozygotes.
It all depends on what you want to accomplish, and how long you are willing to work on the project.
Jim

[robertb]

You need to plant a lot more than five to give yourself much chance! You just keep selecting out the green seeds, and the proportion of homozygous reds increases with each generation. In the forst generation, you have no homozygotes, in the F1, 25%, in the F2, 33.3%, and so on.

[robertb]

No, what am I thinking of? All the F1's are heterozygous. 25% of the F2 are homozygous red, 50% heterozygous red, and 25% homozygous Green. Eliminate the latter. You now have 66.6% red genes, 33.3% green. I'm not sure what proportion of the F3 are going to be homozygous red (it's been almost 40 years since I did any genetics, and a quick google didn't help) but it's going to be more than 25%, that's for sure! In the F4, you've eliminated more of the green genes, so the proportion of red will be higher again.

[jim]

5 seeds was an example to demonstrate the low potential of totally removing all alleles for green seeds from your group....
F1=first generation, F2 is second, and so on....and yes, F1 would be heterozygous...your proportions are a little off Robert...
By the F4, you would still have a relatively high percentage of plants segregating....If you started with a lb of seed from the F2 or F3, and just kept throwing out the green seeded plants, you could likely go decades and still be having green seeded plants pop up...
Jim

[robertb]

My proportions probably are out; as I say it's been several decades. I probably need to get a couple of books on genetics.

[caledonian]

You'd have to do population sorting - grow out the F2 generation, then self-pollinate them, and plant all of the resulting seed separately by parent. If one or more of the plants in each F3 group has green seeds, you know that F2 parent was still heterozygous for that trait.

If you keep only the populations that had only red-seeded plants, and keep selfing them and growing them separately, you can eventually identify populations that must have had a homozygous parent. Keep those populations, and discard the rest.

[robertb]

In the end, the weather was so vile that only Red Eicure and Wizard field beans did well. Even Aquadulce, which I'd always regarded as foolproof from a spring planting, did little more than sulk. I got at least a few seeds off everything, though, and I'll plant them next spring, probably with some additions to the mix.

[12540dumont]

That is sad news indeed.

[robertb]

It's been the worst season anyone can remember, but never mind. There's always next year, and I do at least have some seeds. I got a small crop for the freezer from Wizard, which flourished despite everything.

[templeton]

My autumn sown crop, flowering well - not setting yet, tho.
T

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