Sunroot (Helianthus tuberosus) breeding

[nicolas]

I dont want to hijack the thread on sunchoke x sunflower hybrid with info purely on jerusalem artichoke, and that could serve breeding projects not involving H. annuus. So here is a thread to talk about general info on sunchoke breeding, for example flowering, diversity, fertility, etc.
(Of course one can open another thread for specific breeding projects involving sunchokes)

[nicolas]

So, in my quest to find early flowering fertile clones of sunchokes, i've found interesting infos in the book given by MikeH earlier :

Open-pollinated flower heads from several clones were harvested and threshed to obtain seed
in another Dutch study. Seed was obtained from the mainly early flowering cultivars ‘Columbia,’
‘Topinsol,’ ‘Bianka,’ ‘Topianka,’ ‘Yellow Perfect,’ ‘Rozo,’ ‘Cabo Hoog,’ ‘Précoce,’
‘Sükössdi/Nosszu,’ and ‘D-2120.’ Abundant yields (over 20,000 seeds in total) were recorded, so
despite potential problems of meiotic disturbance, partial male sterility, and incompatibility, open
pollination can produce high seed yields (Mesken, 1988). Seed dormancy was broken by storing
for about 4 weeks at 2°C, and then treating with a 0.2% solution of KNO 3 for 1 week at 10°C.
The seeds were then kept in boxes in a soil–sand mixture under a 28°C day and 18°C night regime.
A germination rate of 60% was recorded for seed from open pollination, compared to 70% from
controlled greenhouse crosses (Mesken, 1988).

[nicolas]

Useful information about flowering, specially for gardeners in northern latitude (like in Europe) :

8.7 FLOWERING TIME MANIPULATION
For cross-pollination between clones, synchronous flowering is essential. Kays and Kultur (2005)
assessed the flowering date and duration of 190 clones (Figure 8.1). Substantial genetic variation
was observed, with the onset of flowering ranging from 69 to 174 days after planting, and flowering
duration ranging from 21 to 126 days. The results suggested that flowering could be manipulated
to some extent by planting date at lower latitudes. However, at higher latitudes growth under
controlled conditions may be required to synchronize flowering.
Latitude has a considerable influence on the flowering time of particular Jerusalem artichoke
cultivars. For ‘Violet de Rennes,’ for example, flowering date varied from June 20 to September
5 to September 30 for plants growing in Tenerife (28°N), Valencia (39°N), and Rennes (48°N),
respectively, with the plants in Rennes failing to produce seed (Le Cochec, 1988). Valencia lies at
the same latitude as the crop’s center of origin in North America. In fact, most cultivars (excepting
very early maturing ones) do not flower or set seed in Northern Europe. Therefore, flowering must
be artificially induced in order to cross using these cultivars in Northern European countries.
Research in the Netherlands has involved exposing numerous clones to varying photoperiods
and temperature conditions. Artificially shortening day length can induce flowering and therefore
the production of seed. Mesken (1988) reported that:



• Short-day treatments of 11 hours induced flowering in most genotypes tested.
• For some clones a duration of 2 weeks was most effective; for others it was 4 weeks.
• For late-flowering genotypes given short-day treatments and grown in greenhouses,
flowering was advanced by 3 weeks.
It was concluded that late-maturing clones should be given an 11-hour short-day treatment for
4 weeks. This induced nearly all the clones tested to flower in time to produce adequate pollen for
crossing purposes (Mesken, 1988). To make crosses, pollen from the male parent is collected in a
paper bag and pollination is carried out by hand using a small brush (Mesken, 1988).

[MikeH]

The Canadian collection which presently gathers 160 accessions is relatively large. It was assembled at the Morden Research Centre of Agriculture and AgriFood Canada during the 1970s. The collection was transferred to the Canadian National Genebank. Plant Gene Resources of Canada (PGRC). in 2000. lt is preserved as a field collection at the Saskatoon Research Centre in Saskatchewan. For enhanced utilization and preservation of the collection. it is essential to provide basic agronomic characterization data describing the material. This study sumarizes descriptive data of the germplasm preserved by PGRC. The objective of this paper was to survey the diversity available in the PGRC collection for improved collection management and utilization of the germplasm.

I think that this is the contact person - www.agr.gc.ca/eng/science-and-innovation/research-centres/saskatchewan/saskatoon-research-centre/scientific-staff-and-expertise-saskatoon-research-centre/diederichsen-axel-phd/?id=1181935680382

Apparently there is also a large collection in France.  

[nicolas]

Thanks for the tip MikeH. Yes there is a big collection held by the Canadian National Genebank. I'm discussing with Dallas Kessler which is a very kind and helpful person.

Some more info on flowering dates of some cultivars :
Genetic Variation in Jerusalem Artichoke (Helianthus tuberosus L.)Flowering Date and Duration

and
Phenotypic diversity of Jerusalem artichoke (Helianthus tuberosus L.)germplasm preserved by the Canadian genebank

[nicolas]

From paolog on the FB group :

I think I discovered something interesting about Helianthus tuberosus seed dormancy. This is the outcome of a germination test involving 20 seeds that were dry stored in the fridge, 25% germination so far after 4 days. Not bad.
All the seeds were dehulled, the pericarp was removed entirely and the underlying seeds were mostly intact. Actually, the intact seeds are still doing nothing, while those, and only those that suffered some degree of damage were like this. A closer inspection showed there is a transparent seed coat beneath the pericarp and the damaged coats in the sprouted seeds detached themselves and fell over. So dehulling non stratified seeds entirely might not be needed as the impermeable layer is probably only the seed coat: once this had been broken the first signs of germination appeared after ~24 hours while the undamaged seeds are still sleeping!
Out of 20 seeds, two decided to rot, 12 remained dormant and 6 germinated. Apparently the degree of damage to the seed coat is directly reflected on the germination speed.

So I took a blade and practiced a tiny incision on the intact seeds on the blunt side (the one opposite to the embrio).
The coat and endosperm are now damaged, we shall soon see if my theory holds true.

If so, then punturing the seed and not fully dehulling it could suffice, that would be good news

[paolog]

Hi!
after that I performed intensive tests on JA seed germination, especially since I suspected that using seeds from just a single mother accession was introducing statistic polarization in the results.
So after testing seeds from about 10 different mothers and 30 different fathers, obtaining ~175 seedlings I devised this protocol and these results:

JA seed dormancy is mostly a mechanical one, induced by seed coat and pericarp. Once both are removed, the main source of dormancy is removed as well. The usual wet cold stratification for 40 days weakens this mechanical barrier and therefore breaks dormancy.

Dry cold storage is probably not necessary, but I've seen that cold storage at 1-2C for just 7-10 days under 0.2% KNO3 followed by removal of seed coat (and possibly pericarp puncturing) and incubation under light with daily highs between 22~28C induces germination within 3-4 days and germination can approach 80%.
Incomplete removal of the seed coat lengthens the time to germination accordingly, with undamaged seed coats the time to germination may exceed 1 month, and what is truly necessary in order to completely break dormancy (and even the residual dormancy not of mechanical origin) is the very short modified cold stratification under 0.2% KNO3 solution.

[MikeH]

Biology and Chemistry of Jerusalem Artichoke Helianthus tuberosus L.  (Note: When I find research of interest, I always add it to the Internet Archive so that it is permanently available

[nicolas]

A document where it is said that non dayneutral sunflowers grafted on dayneutral sunflowers flowers as if there were dayneutral. I dont know if there is interest for sunflower, but it could be interesting for sunchokes ?

Transfer of flowering stimulus from stock to scion in grafted Helianthus annuus
www.jstor.org/discover/10.2307/2439184?uid=3738016&uid=2&uid=4&sid=21103998758511

(cc paolog)

[Joseph Lofthouse]

I have been working on making new strains of sunroots. My long term goals are:

Genetic diversity
Localized to my garden and way of doing things
High Productivity
Short shallow stolons
Winter hardiness
Abundant production of seeds

I started out growing a commercial clone that yields about 13 pounds of tubers per plant. It does not produce seeds when grown in isolation. I attribute that to self-incompatibility.



Then I obtained sunroot seeds from  Kansas Native Plants. They were originally collected as seeds from plants growing wild in Kansas. I planted them and obtained about 30 plants that grew well enough to produce tubers for me. Here is what the tubers looked like: One tuber was collected per plant. The feral sunroot tubers were small. Stolons were as long as a couple of feet which made digging difficult. Productivity was low. They were not knobby which is a trait that the domestic sunroot carries which makes them hard to wash.



Here's a comparison on yield. The productivity of the row of about 30 feral sunroots compared to one plant of the commercial clone.



As a test, I took a few flowers from the feral population and used them as a brush to pollinate a few seed heads on the commercial clone. Viable looking seeds were produced on those flowers, but not on flowers that were not hand pollinated.

I scored each of the feral plants for traits that were important to me, and selected 4 of them to use in a breeding project. I interplanted them into a row with the commercial clone: 4 feral, 1 domestic, 4 feral, 1 domestic, etc... 

The plants grew and flowered. I tested bagging seed heads vs collecting seed shortly after petal drop without bagging. Approximately 20 to 40 times more seed was collected from the bagged heads compared to the non-bagged heads. Goldfinches really get after sunroot seeds!! I saved this seed as "Improved Feral".



The improved feral plants were mostly finished flowering by the time the commercial clone flowered, but there was enough overlap that I collected about 50 seeds that i think were F1 hybrids. The commercial clone is also later to emerge in the spring.

I gave half of the F1 seed to a collaborator in my village. We grew it out. I planted about 25 seeds in the greenhouse, then selected the quickest growing 8 and transplanted them into the field. My field is clayish soil that is irrigated once a week. My collaborator planted his seeds in a dry rocky area. There was a nice diversity among the offspring. One of them didn't produce any tubers that I could find.  Here's a photo of my favorite. It is pretty and has short shallow stolons. It is knobby, ugh. Productivity and size of tubers was great.






A new trait showed up in the fall that I haven't seen in sunroots before. The leaves of two of the plants turned red instead of the typical yellow.




I selected 4 plants from my F1 growout and planted them in a row next to the commercial clone. I just received my collaborators tubers a couple of days ago. The ground is frozen, so in the spring I intend to make another row for his tubers that is next to my row.

We also collected about 60 F2 seeds. The flowers were late forming as is typical of seed grown plants. I expect them to flower earlier next year. One of my plants produced seeds so abundantly that it got noted as the tubers were being harvested.

[matejmag]

Nov 19, 2014 11:43:03 GMT -5 Joseph Lofthouse said:

I have been working on making new strains of sunroots. My long term goals are:

Genetic diversity
Localized to my garden and way of doing things
High Productivity
Short shallow stolons
Winter hardiness
Abundant production of seeds

I started out growing a commercial clone that yields about 13 pounds of tubers per plant. It does not produce seeds when grown in isolation. I attribute that to self-incompatibility.



Then I obtained sunroot seeds from  Kansas Native Plants. They were originally collected as seeds from plants growing wild in Kansas. I planted them and obtained about 30 plants that grew well enough to produce tubers for me. Here is what the tubers looked like: One tuber was collected per plant. The feral sunroot tubers were small. Stolons were as long as a couple of feet which made digging difficult. Productivity was low. They were not knobby which is a trait that the domestic sunroot carries which makes them hard to wash.



Here's a comparison on yield. The productivity of the row of about 30 feral sunroots compared to one plant of the commercial clone.



As a test, I took a few flowers from the feral population and used them as a brush to pollinate a few seed heads on the commercial clone. Viable looking seeds were produced on those flowers, but not on flowers that were not hand pollinated.

I scored each of the feral plants for traits that were important to me, and selected 4 of them to use in a breeding project. I interplanted them into a row with the commercial clone: 4 feral, 1 domestic, 4 feral, 1 domestic, etc... 

The plants grew and flowered. I tested bagging seed heads vs collecting seed shortly after petal drop without bagging. Approximately 20 to 40 times more seed was collected from the bagged heads compared to the non-bagged heads. Goldfinches really get after sunroot seeds!! I saved this seed as "Improved Feral".



The improved feral plants were mostly finished flowering by the time the commercial clone flowered, but there was enough overlap that I collected about 50 seeds that i think were F1 hybrids. The commercial clone is also later to emerge in the spring.

I gave half of the F1 seed to a collaborator in my village. We grew it out. I planted about 25 seeds in the greenhouse, then selected the quickest growing 8 and transplanted them into the field. My field is clayish soil that is irrigated once a week. My collaborator planted his seeds in a dry rocky area. There was a nice diversity among the offspring. One of them didn't produce any tubers that I could find.  Here's a photo of my favorite. It is pretty and has short shallow stolons. It is knobby, ugh. Productivity and size of tubers was great.






A new trait showed up in the fall that I haven't seen in sunroots before. The leaves of two of the plants turned red instead of the typical yellow.




I selected 4 plants from my F1 growout and planted them in a row next to the commercial clone. I just received my collaborators tubers a couple of days ago. The ground is frozen, so in the spring I intend to make another row for his tubers that is next to my row.

We also collected about 60 F2 seeds. The flowers were late forming as is typical of seed grown plants. I expect them to flower earlier next year. One of my plants produced seeds so abundantly that it got noted as the tubers were being harvested.

How is it continue? In Google are interasting colour tubers....
How smoot, big and productive tubers are? From picture it seems like var "aurora red" size ...
Can you send me your seeds? When I would paid to it...
Thank