Wisconsin fast plant crosses/hybrids

Adaptation Projects
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Has anyone experimented with crossing Wisconsin Fast Plants with other Brassica cultivars or species?

I’ve been thinking about an interesting long-term breeding project and was curious whether anyone here has tried something similar.

The idea is to use Wisconsin Fast Plants (the rapid-cycling Brassica rapa lines) as a breeding platform while introducing novel traits from other B. rapa cultivars and possibly even other Brassica species.

Within B. rapa alone there seems to be a huge amount of diversity:

  • Turnips with enlarged storage roots
  • Pak choi and bok choy with thick petioles
  • Mizuna and mibuna with highly dissected leaves
  • Tatsoi with its compact rosette habit
  • Napa cabbage with heading growth
  • Purple and anthocyanin-rich varieties
  • Oilseed forms and various landraces

It would be interesting to see whether repeated backcrossing and selection could retain much of the rapid-cycling life history while incorporating some of these more unusual morphological traits.

I’m also curious about the potential for wider crosses within the Brassica genus. Has anyone worked with hybrids involving:

  • Brassica nigra
  • Brassica oleracea
  • Brassica juncea
  • Brassica napus
  • Brassica carinata

I know many of these relationships are summarized by U’s Triangle and that interspecific hybrids can have reduced fertility or require chromosome doubling to restore fertility, but I’m interested in hearing about real-world experiences rather than just textbook compatibility.

Some traits that seem especially interesting to introgress (if possible) would be:

  • Purple stems and foliage
  • Novel leaf architecture
  • Compact or rosette growth habits
  • Larger flowers
  • Increased branching
  • Unusual seed color
  • Enhanced drought tolerance or heat tolerance

I’m not necessarily aiming for an agricultural cultivar—more of an experimental or ornamental breeding project that takes advantage of the incredibly short generation time of Wisconsin Fast Plants.

Has anyone attempted anything like this? Which crosses were easiest, which failed completely, and were there any surprising phenotypes that appeared in later generations?

I’d love to hear about successes, failures, photos, or papers that document similar breeding projects.

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Hey, I haven’t started this yet, but I was considering basically this exact thing for my indoor grow project this winter. I came across your post while researching, and you’re pretty much the only other hobby breeder I’ve found who suggests something similar.

I think there could be room for something like a Brassica version of the Dwarf Tomato Project (maybe a “Rapid Edible Brassica Project”) that uses rapid-cycling genetics to create micro rapini, micro broccoli, baby Napa, compact pak choi, etc.

You mentioned being more interested in experimental/ornamental plants, but what really interests me is taking the same idea and selecting specifically for useful edible phenotypes while retaining the crazy-short generation time.

I found RCBC Seeds, which maintains rapid-cycling populations of B. rapa, nigra, oleracea, juncea, napus, and carinata. Interestingly, their 1-171 B. rapa line apparently originated from crosses involving multiple B. rapa vegetables and multiple rapid-cycling lines, so there’s already some proof of concept for doing this within B. rapa.

I’m basically thinking of two separate genetic “lanes”:

B. rapa: rapid-cycling B. rapa × rapini, Napa, pak choi, tatsoi, mizuna, etc.

B. oleracea: RCBC 3-1 × broccoli, cauliflower, kale, etc.

I think the B. rapa lane is especially appealing because RCBC lists a complete generation at roughly 36–40 days under good conditions. With an indoor setup, I could potentially push through 5 or so generations between now and when I need the space back for spring seed starting.

B. oleracea is slower (around 70 days/cycle for RCBC 3-1) but still drastically faster than doing a conventional multi-year vegetable breeding project.

Logically, I think it makes sense to lean into what rapid-cycling Brassicas already want to do: flower and reproduce extremely quickly. So rather than immediately trying to force something like a heading cabbage into a 40-day life cycle, I’d start with vegetables where the reproductive structure is actually the part we’re eating. Developing root vegetables like turnips would be the most difficult.

Rapini seems almost ideal because “flower as fast as possible” and “produce the crop as fast as possible” are basically the same selection pressure. Broccoli is similar, although obviously, you’re also selecting for a worthwhile amount of edible inflorescence before the flowers open.

A few crosses I’m particularly tempted by:

1-77 anthocyanin dwarf × rapini - select toward a purple, miniature, ultra-fast rapini. Sorrento looks like a promising conventional parent. Something that’s maybe only 6–10 inches tall but produces a respectable little edible flower cluster extremely quickly would be really interesting.

RCBC 3-1 B. oleracea × De Cicco broccoli - select for very early heading plus De Cicco’s branching/side-shoot tendency. My mental image is basically a little broccoli bonsai covered in miniature edible shoots.

1-135 rosette anthocyanin dwarf × mini Napa - probably a harder project because early flowering and heading are somewhat competing objectives, but potentially something like a tiny purple “bonsai cabbage” or very compact edible rosette.

I’d probably measure things like days to first edible harvest, plant height/footprint, edible yield, branching, days to flower, and total seed-to-seed generation time rather than just selecting for earliest flowering.

I’ve never done serious plant breeding/crossing myself, but it’s something I’ve wanted to get into. I understand the general genetics and selection process reasonably well from researching tomato and micro-dwarf tomato breeding last year, so this seems like a fun species to actually learn on because you can see several generations in one winter instead of waiting years.

Have you done anything with this since posting in June, or is it still just something you’re considering?

I’d definitely be interested in collaborating. Even with only 2–3 people, we could divide up crosses or split F2/F3 populations between growers, select different branches, and then exchange the most interesting material. It could be a fun little open-source breeding project rather than all of us reinventing the same thing independently.

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So one snag I’ve run into is trying to obtain these seeds in Canada. Ayva Educational Solutions seems to be the only authorized seller for Carolina Biological within Canada, and they charge a mandatory $150 phytosanitary certificate + $40 shipping on all orders.

RBCB will ship for $40 without the $150 certificate but they don’t have the specific “Astroplant” variant that I think would do best for this breeding project. There are problems with the ros/ros dwarf plants where they produce much less gibberellin and have issues where you need to either use acid to break seed dormancy or let them sit for months after harvesting for it to happen naturally, which kind of defeats the purpose of a fast-cycling plant. I need the dwf1/dwf1 genes and specifically “Astroplants” is an improved version of the “Petite” variant.

I’m thinking of emailing a university near me with an agriculture / plant sciences program and see if they’re willing to send me 20 seeds to experiment with. They’ve published previous papers using the Astroplant fastplant seeds specifically so I know they at least had them at some point in the past. Would that be weird, or do they frequently get those types of queries?