I've been working on making wide crosses within the Phaseolus vulgaris group of species since last winter, with a number of different varieties of common, runner, and tepary beans. In the process, I've also made a few crosses between different varieties of the same species. For now, I've mainly just been practicing my technique and working my indoor growing setup, which is a couple of shop lights in the basement with good enough light isolation to get seed from short-day varieties.
In the process, I've started to accumulate a fair number of candidate crosses. I say candidates because I strongly suspect that most or even all of the seeds I have are from poor emasculations or from pollen of the same species contaminating my tweezers. There's one possible runner x tepary and several tepary x common seeds that are especially unlikely since the literature says these crosses always require embryo rescue.
I'll post some more details on the project in the next few weeks.
For now, I'd like to ask for advice from the expert bean-growers out there, since I'm about to start growing out these candidate crosses. How do you germinate and grow weak but valuable bean seeds?
andyb can't comment so much on weak bean seeds - but I've been germinating some weak pea seeds. My method is to germinate them in a covered plastic Petrie dish on filter paper. I've found the weaker the seeds are the more likely they are to rot. I keep a close eye on them and as soon as I see any fungal filaments I make a cup (one teabag) of pure camomile tea, then take about 1/5 cup of the tea and dilute that into another cup of cold water and use a little of that as a rinse. Be sure not to leave excess water in the Petrie dish. You may need to repeat the rinse every day or few days until germination occurs. Then once you've got cotyledons pot up and away you go. Hope that helps.
Thanks, steve1 . I'll try some chamomile if I get mold. I think for my first try, which I'm planning to start tonight, I'll use a germination-test setup with a damp paper towel in a partly closed snack ziplock.
Here's my current inventory of potentially crossed seeds. The landrace runner is one that I received in trade at a local seedswap. I also have three more common x runner pods drying down in the garden. Most of the seeds are smallish or normal with the exception of a single Golden Gaucho x landrace runner seed, which is about 50% larger than normal. I wouldn't be surprised if it's the only one from a real intraspecific cross.
common x runner Golden Gaucho x landrace runner, 3 seeds Golden Gaucho x Moldovanesti Buffalo, 1 seed Fort Portal Violet x Moldovanesti Buffalo, 4 seeds Fort Portal Violet x (Restoration Seeds) Scarlet Runner, 4 seeds
tepary x common (unlikely to be real): Paiute White x Golden Gaucho, 1 good seed, 2 shriveled seeds
runner x tepary (unlikely to be real) landrace runner x Blue Speckled, 1 seed tepary x tepary Paiute White x Blue Speckled, 1 good seed, 5 shriveled seeds common x common Golden Gaucho x Calypso, 5 seeds Black Coco x Bola Roja, 1 seed
steve1, I'm less than a year into this project so I'm far from being an expert, but I can share some of my experiences so far. There's also an older thread, Breeding Beans, that has lots of good information. In particular, there's a link to a guide for crossing beans: bean_pollination.pdf.
For the wide crosses, I've been doing full emasculations and have been making up the technique as I go. I use sharp, straight tweezers and always wear a pair of magnifying glasses, which have a side benefit of making me look stylish and sophisticated.
The best way I've figured out to do full emasculations is to stab one side of the tweezers all the way through the tube of the keel about 180 degrees from the hole at the end and then slide them sideways out through the end of the keel. This allows you to remove the last bit of the keel to expose the anthers and stigma without damaging the stigma. After that, it's relatively easy to remove the anthers.
When I'm collecting the stigma with the pollen, I trip the flower and use tweezers to grab the stigma right where it comes out of the keel. I was having trouble with the pollen shaking off the stigma until I figured out that I could hold the tweezers and the stigma steady while pulling the flower away with the other hand, rather than the opposite.
If you're like me, you'll probably end up destroying some flowers early on. Have fun, and let me know if you figure out any tricks of your own!
I don't think the tepary x common cross is likely to work without embryo rescue. I have heard about spontaneous commonXrunner crosses so I'll be very interested in seeing what results you have. Messing with bean flowers is a nightmare, I admire your patience.
andyb thanks for that. I've been approaching the pollinations in the same way I've been working on peas with the added pain of working on climbers which encompass my favorite high yielding varieties growing outside. I'll give your method a crack maybe with a couple of plants in a poly tunnel. Good luck with the wide crosses. Do you have any plans to chromosome double the wide crosses to maintain both sets of parental chromosomes?
oxbow, I agree on the tepary crosses. One of my main goals with them was to learn what pods look like right before they abort, so I'd have some idea when to pick them if I ever attempt embryo rescue. It was surprising and a little disappointing to see some of those pods swell up and grow just like selfed ones, which they probably were. At this point, though, I feel like I need to treat those seeds as if they are real crosses and grow them out carefully and at the same time as plants of the parent varieties so I can potentially make backcrosses.
steve1, the jug of oryzalin arrived a couple of days ago .
One of the projects I may attempt long-term is a cross between runner beans and teparies, with the goal of a fall-planted crop that would grow without irrigation in the Pacific Northwest and mature in mid- to late summer. Some runner beans can overwinter here, and if they got the drought-resistance and deep roots from the teparies, they might be able to mine the deep soil for water and mature pretty late. Making an allotetraploid would probably be the best way to approach this project, depending on how difficult chromosome doubling is relative to the embryo rescue / congruity backcross route. It would be a wildly ambitious project to take on as an amateur, but it's fun to daydream about.
Short term, and with the common x runner cross(es), I'd like to do a few rounds of congruity backcrossing before planting out and selecting. This would put the first big growout in the summer of 2018, with a lot of tweezer work between now and then.
I have a common x runner growing now. It came to me that way in a seed swap. Small, Cherokee Greasy beans grew a single plant with red flowers that made a bluish, purple bean. I only had a few seed cause deer ate most and only one grew well this year. It is a huge vine with a fat stem and pink flowers. It has a good crop of large fuzzy pods. Should have dry ones in another week or so.
Also have a common x common that showed up in my garden. The mother was Ideal market, a black seeded pole bean and the father was most likely KY Wonder although it could also have any number of others. The F1 was a large tan colored bean. The F2 has some black ones, speckled ones, tan and a large white bean. Pods varied in in size with some being purple and some green with purple streaks.
I think crosses happen naturally a lot more than commonly believed. It seems rare because they don't show up the first year and most get eaten rather than planted. A technique I think will work to get crosses is just to grow a single plant of one kind in a patch of a different kind and saving its seeds.
Nothing ruins a neighborhood like paved roads and water lines.
This is my Ideal Market (top left) x what I think was KY Wonder. Top right is the F1 seed that I found last year in the Ideal market patch. Bottom row is all the kinds that grew from those seeds this year. This is the first time I have seen this and known for sure that's what happened. It's amazing. Now from what I understand I will get still more segregations next year.
I'm also more sure now that some of the other weird beans I found last year are probably also crosses. I didn't grow the others out this year. I don't know what to do with them all as I don't have room to grow out lots of variations seprerately. I guess I'll just add them to my pole bean land race. Should have some pictures of the suspected common x runner cross soon.
That's some nice segregation! I particularly like the white one with black speckles and its inverse.
Do you happen to remember what your common x runner F1 plant looked like when it was growing? I went back in the archives and saw a picture of it when it was drying down but didn't notice any from when it was younger.
That plant really stood out because of its red flowers but didn't look any different otherwise. I guess I lost most possible segregations because I just had one do well this year. It is a huge vine with pink / red flowers. Don't have any dry seed from it yet. Also don't know the F generation of the cross since it came to me that way. I'm suspecting that some of the other blue/purple seed I got last year might be related to it.
Nothing ruins a neighborhood like paved roads and water lines.