Creating and Discovering crosses in common beans

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do you mean the bean itself does not show a difference when crosspolinated ? Last summer I discovered different colours of beans in different pods on the same plant. So I assumed they were crosses. Am I wrong ?

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I believe that means there was a cross in the previous generation. In beans, the F1 doesn’t show anything visible on the outside, but the F2 and thereafter does!

Definitely save those beans and plant them. If they were all on the same plant, that means that plant was definitely the product of a cross, and has a ton of heterogeneous genes to work with. You may see even more interesting segregations down the line.

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@isabelle, are you 100% certain that all those seeds were from the same plant? Absolutely no chance of a mix up? I have always thought that the skin of a bean was maternal tissue and so would be the same for all beans on one plant. Of course, shade variation occurs as does pattern reversal - those grey speckled and black speckled beans in the upper right of the photo are classic examples of pattern reversal. I may be wrong here but I cannot see how there could be different colours on the one plant, even if it was a segregating cross. If I am wrong here, and I’m not an expert on the inheritance of seed coat colours, I’d love it if someone more knowledgeable would chime in to correct me.
Edit: I wonder if a somatic mutation might cause a branch to produce different coloured beans. In the horticultural industry such mutations are called sports.

@MarkReed How different are the seed coats of the beans you grow? I grow lots of beans but usually each in its own row though the rows are often next to each other. As you point out, crosses can be easily missed. I was thinking next season I would plant a row of one variety and plant individuals of a different variety among them just to see if I could encourage a cross or two. Those individuals would be saved separately and planted out the following season. I figure it’s very little extra work and if no crosses turn up I still have beans to eat.

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My experience is also that beans (and peas) are consistent within a plant when an oddity arises. A couple years ago, I grew out a row of regional heirloom beans from a bag I bought for cooking and discovered two very different bean types in the grow out - small oval seed produced a mix of oval and cutshort beans, although all pink. I have an envelope of what I think is an F2 of rattlesnake and blue coco beans that I want to grow out. However, I currently have a toddler who doesn’t believe in leaving beans or peas on the plant beyond the chomping raw stage.

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F2 means it produces seeds that produce genetically different plants, but single plant is still uniform. There might be some variation how colour appears, but within limits. Some seeds might be more developed and therefore have different colour. I had some beans I did not regonize after they had been in storage because I never saw them fully developed. What had been white backround colour had turned into pink.

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Wow! And here I thought colors faded with time in storage! (Or is that only true for peas?) Pink beans sound really pretty!

Some might, but what I meant in this was that the colour had not fully developed in those and continued developing. Might have been just few more weeks that they were fully coloured. Someone with longer season might have missed that or then had slighly different colours depending on stage where those beans are.

Oh, interesting! So you harvested them before they were completely developed, and they managed to finish maturing in storage? That’s cool!

Seeds were fully developed and mature, but they had not dried up completely which is part of the colour difference. Something also happens during storage, but I don’t know why is that. Maybe it’s that they really dry up completely. During growing first pods start to turn maybe 2-3 weeks before end of season and that last part isn’t that dry so usually only few pods are completely crisp at the time of harvest. Might have to collect them before that if weather is too cool/wet for drying and there is change of spoiling.

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That’s really cool! Is it possible they’re F2 crosses that you’re only noticing now? Or are they definitely F1 crosses? I’ve read that F1 crosses are invisible in beans, because the pericarp is maternal tissue; it would be cool if that isn’t always the case.

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Now I need to go read Mendel.

thank you everybody for this interresting discussion.


If one plant gives only one type of colour, then I must have mixed up my crop. It may be that my various coloured beans do not come from the same mother. Ok, I can accept that.
It was the second summer I grew beans, so the cross might come for the previous year. Still, they are hybrids, htey must be because I never sowed such coulours of beans, especially the speckled one. Whether F1 or F2 is not so important to me.
This is how they look now after a few month of storage . three of them seem related like father, mother and son.

if the coat is mother material, how come I only have a couple of beans with the mixed coat colour ?
anyway all this is very very exciting. I am very impatient to see them growing amongst the others. I just marked these ones to try to follow up.

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Possible but unlikely. The year I saw the orange and purple-speckled mix the two seeds were from different sources and it was the first year I planted them. If it was the whole plant, or even all the seeds in a pod, I probably would have assumed that it was just the way the beans grew. But just one bean in a full pod? That’s mixing.

It doesn’t seem to happen often, and more with some plants than others. I saw pink beans in the pod of a white bean, but no light beans in the red bean it apparently crossed with. I see no mixing in the black beans, but once in a while I’ll see something that could be a mix, like a dull bean in a pod with shiny beans.

I haven’t had the time to do the test Joseph Lofthouse suggested–plant a row of white beans, and a row of colored beans right next to them that you know are unrelated. Then check every white bean pod for crosses.

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@MarkReed , @RayS thank you for the explanations about colour reversal. so the black and speckled may be of the same plant, and it would not mean they are hybrids.
As far as those that where white in autumn but are more yellow now are concerned, they may come from the same plant as the orange/brown ones, without hybridation.
So this bunch marvelously colored that looked to me like at least 4 or 5 different genetic material could very well be only 2.
So my mix-up could be of only 2 plants and not 4 or 5. And it may be that there are no hybrids whatsoever in there. Pity, but interesting lesson.

Coming back to Mark’s plan to make sure you keep hybrids for seeds instead of eating them , since I have already sowed my beans all mixed up, what about keeping one bean of every pod produced this coming season (and eating the others ) ? would that ensure I pick all the hybrids or at least most of them ? Of course it would mean increasing considerably the space of second year planting … (this I can do).

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Unfortunately no, since a hybrid might be any bean in the pod. A bit of pollen pollinates only one bean.

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thank you mark for all these explanations. I love learning what needs to be observed and distinguished and in the future I will look even more closely to the ranges of shapes and colors of my beans.

This year is the first year I mix them. I love the idea of no longer caring about varieties and just cultivate the bunch of them. I may not obtain crosses but at least I have some genetic diversity (about 20 varieties initially) and I will get adaptation to my soil and cultural practice.

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Thank you Mark, now I will do this with the Lofthouse bush beans. I have been hoping somebody could figure out how to figure out how promiscuous they are, and then how to move them towards most promiscuity over time… This seems like the best plan; changes could be trackable over time.

How does this sound?
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  • Plant two, 150 ft rows. 6" spacing. So 300 plants per row (I’ll seed @ 3" apart and thin), 600 plants. I could plant 100 of each color, with a flag marker between them.

  • Then when harvesting, I look for any plants in that block with an off-color bean, I will only have to look at a single pod. Record and add to the separate bag of natural hybrids.

  • Then I total up the # of off colors, divide by # of plants in the rows, and get a promiscuous percentage… does that sound right?

I suppose ideally I’d plant a control block of heirloom beans to get a starting promiscuity difference in my location but I’m unwilling to go that far :slight_smile:

((I planted a separate mix of heirloom beans last year and got hardly any compared to my 15 lbs of promiscuous beans! The P. beans germinated way better, were a month earlier, and much more vigorous, so I assume they have naturally been hybridizing but I didn’t know how I would know that. ))

Any suggestions or preferences of which colors here I should prioritize looking for natural hybrids?

Joseph L and I recently sent in a few lbs to the bean steward @clweeks that will be bagged up and available soon for anybody who wants to grow them out this season, and I still have extra, so if anybody wants to try this project on a single color theoretically I could send you some once I do some sorting.

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I first (and second, and third) read 2,150 row feet and thought that’s lots of beans. I have some of Josephs beans and I thought I would also plant them separetely like Mark to look how much they segragate, but also to know which are different to make some manual crosses. Between Josephs, but also to add some new varieties.