Is anyone working on convincing beans not to self pollinate so easily? For our purposes that would be a good thing, but for those trying to preserve an heirloom variety, not so much.
I have an idea for a process, but I’d like to hear what other people think in general.
Is it worth it? Would there be any benefits, other than inbreeding and making breeding in general easier?
In my experience, some beans are willing to accept foreign pollen more easily (partially self infertile? Release pollen later?) While others only spread their pollen from open flowers and don’t set crossed seeds as easily.
If I can get a group of natural crosses, I start with a group that will cross and automatically eliminate those that won’t. If I can’t get a group like that I can create it but it’s going to be more complicated and time consuming.
Once I have a population consisting only of possible outcrossers, I think I can eventually get to a population that consistently crosses. Then I can let the plants do the work.
Problem with beans is that their flowers aren’t suitable for cross pollination and hence SI would be just a deadend. Most sources say about 1% crosspollination rate in beans. That would have to go way up for SI to be viable. Favouring crosses would on average favour outcrossing traits, but that process is extremely slow and might not make that big of a difference. You could speed up the process by looking at flowers more carefully to see if you can find one with a mutation that makes outcrossing easier. That would be quite painstaking work without any guarantee that you will ever find anything useful, but without you might miss something that would make a big difference. Like if some plant has 10% outcrossing rate, there is no guarantee that any crosses will happen, and if they happen, they might get eliminated by climate, pests etc before producing. I myself should also look at the flowers and compare them more carefully. I remember a few years ago when I tried (unsuccessfully) make hand crosses on bush beans that the flowers looked like it would be really hard for outside pollen to get to the stigma. Maybe there are some differences. I doubt finding something with 10% (or higher) outcrossing rate is realistic, but 2-3% is already much better than 1%.
I you plant a single plant of one variety among a patch of another variety, assuming you have good pollinator activity the chances of finding a cross increases significantly. Problem is seeing that cross in the first generation is very unlikely. Instead, to find them you have to plant all of the seeds from that single plant the next year and since a single plant can make hundreds of seeds, and if you garden is small, like mine you have to abandon other crops just to have room for it.
I have done that very thing, and I have found a number of random crosses, including from packets of purchased seeds. A black seeded bean called Cherokee Trail of Tears seems to cross more readily than most. I’ve found off types in growing newly purchased seed.
I spent some time tracking and documenting confirmed crosses, it gets harder every year because segregation continues for years and it’s impossible to know every time you see a new bean if it is a new cross or a segregation from one that happened three or four years ago.
I was never able to document any noticeable improvement in vigor, disease resistance or production from any of the confirmed crosses. Now, if I see what I’m sure is, or might be across I do make a point to include it my dry bean mix the next year. If by chance a crossed bean truly is superior in some way it will be revealed in a greater number of seed produced, but I have never really seen that happen. If it did, I wouldn’t pay any attention other than that, and I wouldn’t give it any special treatment. It would just part of the ongoing mix. This applies much more for dry use than as green beans because only those few you pick out for seed ever make it the ground the next season with green beans.
Overall, I think common beans cross more easily than is generally believed but it may be environmentally specific, a good population of pollinators is certainly required.
Runner beans and Lima beans supposedly cross much more easily but I have grown them for decades and never once found a cross. I’ve also never found one in cowpeas.
My plan was to grow two very different bean plants indoors, pollinate with a paintbrush after the flowers open and look for visual crosses. Plant them to see if they are true crosses, plant the rest in their own population group, and identify which of the initial parents (if either) had a high percentage of crosses. This would suggest to me that either that plant releases pollen later, or it doesn’t fully pollinate.
That wouldn’t be very effective. If you grow them over the winter, I would rather try to emasculate the ones you are trying to pollinate. While doing that you could see how weird those flowers actually are. Or just look at them more closely next year. Changes are that with paintbrush you are not going to make any crosses, unless you do massive amount of them, and like Mark said, you might not be able to distinguish them visually even if you get some.
It might altho I’d think recently successful hybrids within a cultivated species can function like a wild type species for helping with wider outcrosses.
Since P. vulgaris x P. coccineus hybrids happen naturally, it should’t be any more harder to do it manual yourself right? Both are in the Section Vulgaris.
I feel like the problem with the flowers have more to do with the flower shape rather than the pollen compatibility.
The shape of Phaseolus vulgaris strongly leans towards selfing as the flowers pollinated themselves right as they open.
I may be wrong but it seems pretty straight forward if you get the flowers before them open & carefully bring multiple different sources of pollen over to the style.
I think this makes sense as wasn’t the Cherokee Trail of Tears bean more of a wilder/landrace type of heirloom similar to how Seminole Pumpkin isn’t too inbred?
I think this makes sense, If I recall Correctly P. vulgaris self pollinates before flowers open but that isn’t the end all for sharing it’s pollen with others, it might still be open enough to receive pollen as well, kind of like a mini mentor pollination techinque happening.
I don’t know the origins of Cherokee Trail of Tears; I figured the name was probably mostly just a romanticized thing. Another black bean called Ideal Market throws a lot of off types too, or rather other beans grown nearby to it do. Same, I guess with CTT, they pollinate others as much or more than being pollinated by others, but that’s just from an observation or two, I can’t say anything for sure. A family of beans called Greasy do that too and they may be a bit more wild because dry pods will sometimes shatter on their own when dry. I had a greasy bean with red flowers one time, but it did not produce an acceptable amount of beans for the space it took up. There is a bean called Refugee, it is supposed to be very old. I got some from Monticello and found an off type in the original thirty seeds I bought. I tracked them for a few years and even named some, but they just kept segregating and are now just lost in the mix, assuming they haven’t selected themselves out. It’s just more trouble than it’s worth keeping track.
I’ve grown common beans, runner beans, lima beans and wild thicket beans close to each other for a long time, but common x common is the only off-types I have ever found. I wish I could say that he crosses grow or produce better, but they haven’t. They are just a different color than the parent(s).
When I started growing more for use as dry beans is when I started finding more crosses in pole beans. I think that is probably just because I see more of the dry seeds. I don’t grow as many bush beans, and they are mostly to eat as green beans, so I don’t see crosses in them.
If something more productive or more adapted ever really does show up in my beans, I figure it will just end up representing a greater percentage of the total, whether I keep track of it or not. Looking for them and giving any special treatment for the sake of finding crosses interferes with the goal of growing stuff to eat.
From what I have seen there may be many more crosses than are recognized. Pink beans in the pod of a white bean growing next to a red are possible, but I’ve never seen paler pink in the pod of a red bean. There may be crosses in the other direction, but they’re not visible in the seed coat.
This year I got two unpatterned dark beans in a violet striped population. Possibly crossed with an unpatterned black? You wouldn’t be able to see crosses in the other direction, they would just appear black.
That’s what I was thinking. You would need to select for a more open flower structure.
I was thinking that may be more common in wild species but if it could be achieved through crosses with any other domesticated Phaseolus that might be less work.
Another variety that clearly crosses more easily is “Coco rose de la Meuse”… A seed producer told me that he always found crosses in this old variety.
We could already make a list of these frivolous varieties to try to bring them together in our gardens.
I also have “Cherokee Trail of Tears.” I could plant them next to each other next year. The hybrids will surely be easy to find with two completely different colors and seed shapes.
but what about the embyro size? A seedcoat can’t hide the physical size of hybrid embyro, especially if a small bean seed crossed with a huge bean seed like Tepary x Runner beans.
It might look like Huge beans in tepary pods & small beans in Runner pods.
That’s gonna be hard to do, as the defining characteristic of the Phaseolus genus is the twsited coil keel. It might be easier to just work with Vigna or Lablab beans.
There is a possibility of size being affected. Most scientists say not a chance, but there are often beans that are deformed (too large, too small, twisted, split) which are discarded in harvest.
Thousands of years of selection may be responsible for their homogeneity rather than nature.
I suspect that some of the directional crossing (smallerxlarger more likely to create viable seed) is because of physical constraints of the plant itself.
