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Sunchoke breeding? Yeah, that'll do for a little rant tonight.
It is clearly late enough into winter that I'm thinking about what I'll be planting in the spring gardens.
It is clearly late enough into winter that I'm thinking about what I'll be planting in the spring gardens.
Didn't happen last night, but I've still been thinking about it.
"Sunchoke" is a common name (among many) for the large tuber producing sunflower, Helianthus tuberosus.
The tubers are largely filled with inulin, a polymer of fructose. (Similar to starch, a polymer of glucose.)
"Sunchoke" is a common name (among many) for the large tuber producing sunflower, Helianthus tuberosus.
The tubers are largely filled with inulin, a polymer of fructose. (Similar to starch, a polymer of glucose.)
The plants can produce a surprising about of food if they're happy. https://twitter.com/thebiologistisn/status/1318644744961011719
Most articles describe the tubers as having a short storage life because they dry out. Kept moist, they can be stored far longer.
My method is to put them in a sealed ziploc bag with a splash of water, then in the fridge bottom. They've lasted 1.5 years this way.
My method is to put them in a sealed ziploc bag with a splash of water, then in the fridge bottom. They've lasted 1.5 years this way.
Sunchokes are self-incompatible, so you have to have at least two distinct varieties to do breeding work with them. Many varieties are available, ranging from very domesticated with large tubers to much more wild with smaller tubers.
The species is widely distributed across the eastern half of the US. Native peoples domesticated the species into a crop and even now larger tuber forms are more likely to be found growing where people lived before European colonization.
Since the species hasn't been integrated into modern monoculture agriculture, it has largely been ignored by institutional plant breeders.
So. What have smaller scale plant breeders been doing?
So. What have smaller scale plant breeders been doing?
Improving productivity, reducing plant size, making easier to clean tubers, improving taste, changing flowering time, and changing flower color are all goals which have been mentioned by folks working with the species.O
One of the more interesting goals I've encountered is to convert the inulin into starch, making it more generally digestible. (Eating too much too quickly can lead to digestive upset because our gut microflora aren't usually used to inulin.)
This would be a relatively simple tweak to the physiology. Some basic lab analysis of seedlings to identify a shifted inulin to starch ratio would be needed. This might be out of range for a small scale breeder.
So. What have I been doing? (If you've followed me for a bit, you are probably pretty confident that I've been doing something.)
My goal has been to increase productivity. This is a little presumptuous given how productive they already are, but let's go with it.
My goal has been to increase productivity. This is a little presumptuous given how productive they already are, but let's go with it.
My idea has been to hybridize sunchoke with one of the giant sunflowers. https://twitter.com/thebiologistisn/status/1308873658815967234
Sunchokes are hexaploid, with six copies of each chromosome. Domesticated sunflowers are diploid, with two copies of each chromosome.
Differing chromosome numbers are often a problem, producing an infertile hybrid. (Diploid [2n] x tetraploid [4n] -> triploid [3n], for example.)
Differing chromosome numbers are often a problem, producing an infertile hybrid. (Diploid [2n] x tetraploid [4n] -> triploid [3n], for example.)
However, in this case, the hybrid ends up being tetraploid [4n]. Having an even number of chromosome copies allows it to be fully fertile!
That first season I had several hybrids. One was outstanding.
Each flower was fertile and was developing numerous seeds.
This would be great, but I messed up. That fall I was moving to a new home and tried to harvest the seeds before they were ripe. That didn't work.
This would be great, but I messed up. That fall I was moving to a new home and tried to harvest the seeds before they were ripe. That didn't work.
I then left the plants alone until the first frosts. I went back to the old house and (with permission) dug up the plants.
A couple had an obvious tuber. Those and the root crowns lived in a fridge that first winter.
In spring, only one (from the largest plant) woke up.
A couple had an obvious tuber. Those and the root crowns lived in a fridge that first winter.
In spring, only one (from the largest plant) woke up.
That plant has since been living in my yard. It blooms every year, but hasn't produced any further seeds.
This tells me the hybrid inherited the self-incompatibility of the sunchoke parent.
This tells me the hybrid inherited the self-incompatibility of the sunchoke parent.
The plants have never gotten as large as that first year.
This could be because of the less rich soil they're now in. (Heavy clay the 1st year, but almost pure sand now.) It could also be the plant which survived that 1st winter was from one of the smaller hybrids & lost track.
This could be because of the less rich soil they're now in. (Heavy clay the 1st year, but almost pure sand now.) It could also be the plant which survived that 1st winter was from one of the smaller hybrids & lost track.
This year I'm setting up to recreate the hybrid. With multiple hybrids, I should be able to produce more seed to keep the project going.
I'm also planning to transplant my existing hybrid to a new location with better soil. Next year I'll see if it will grow taller.
I'm also planning to transplant my existing hybrid to a new location with better soil. Next year I'll see if it will grow taller.
My initial hybrid has turned out to be a wonderful plant all on its own.
It wakes up in late spring. Always late enough I find myself wondering if it survived. But then there it is.
It spreads slowly, unlike its sunchoke parent, making it a very polite landscape plant.
It wakes up in late spring. Always late enough I find myself wondering if it survived. But then there it is.
It spreads slowly, unlike its sunchoke parent, making it a very polite landscape plant.
A couple years back I potted up a division to be planted in another yard, so I could see how it did with different soil. That plant didn't get planted into the ground and died. So... Next time I give someone one, I'll be planting it for them.
It propagates slow enough that it would take some effort to produce it for any sort of distribution. I may set about this anyhow.
My expectation is that I'll be able to recover more abundant tuber production in the next generation, once I've constructed another hybrid to overcome the self-incompatibility seen.
Eventually I'd like to get a plant which combines good tuber production of the sunchoke parent with the giant growth traits of the sunflower parent.
Others have explored this hybrid before. http://bulbnrose.x10.mx/Heredity/sunflowerXchoke/sunflowerXchoke.html
Much of the work I've been able to find has focussed on introgressing disease resistance or perennialilty traits into commercial oilseed sunflowers.
I haven't read of anyone else aiming to bring traits from sunflower into something mostly like sunchoke.
I haven't read of anyone else aiming to bring traits from sunflower into something mostly like sunchoke.
