Author Topic: Perennial Sunflower (Helianthus) Breeding  (Read 553 times)

Johann Kuntz

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Perennial Sunflower (Helianthus) Breeding
« on: 2021-08-24, 01:51:59 PM »
I've been working on producing a hybrid swarm of sorts of sunflowers combining genetics from annual sunflower as well as various perennial species.  I've been learning a lot.

I know that there are a fair number of people who have been interested in hybridizing Jerusalem artichoke (Helianthus tuberosus) with annual sunflower (H. annuus) in hopes of producing tuber crops with improved diversity of traits to select from.  Note: this hybrid produces tetraploid individuals which would be intercompatible with eachother for future crosses, but would result in sterile triploids and pentaploids if back-crossed with either the H. annuus or H. tuberosus parent respectively.

The primary challenge holding most people back is getting bloom overlap between the annual sunflowers and the Jerusalem artichoke.  Based on my experiences so far a number of people are on the right track by attempting to use early blooming selections of Jerusalem artichoke for this cross.  However, it is also helpful to simply plant your annual sunflower seed late (and in pots).  The combination of planting them late as well as growing them in pots results in plants which are significantly smaller and portable with a later bloom time.  This means you can easily reach the flower heads for hand pollination even if using genetically large selections of annual sunflower.  Additionally, many wild forms of annual sunflower naturally bloom later than the cultivated types on account of not having had intense selective pressure for agricultural purposes.  If you don't care much about large flower or seed size in the annual parent it can be a very good option to use these wild types which not only naturally bloom later, but also typically have branching with multiple flower heads which results in an extended bloom time.  If you are using a single headed variety of annual sunflower and find it is beginning to initiate flower heads too far in advance of your H. tuberosus, you can actually initiate secondary flower heads which will bloom later by pinching the terminal flower bud while it is still small.  The resulting secondary blooms will be smaller and possibly deformed, but they will still contain the correct genetic material needed for producing the desired hybrids.

When making this cross it is important to use the H. tuberosus parent as the seed parent and the H. annuus parent as the pollen parent.  Two reasons for this. 
  • Many cultivated forms of H. annuus have some degree of ability to self pollenate which means that it would be difficult to prevent self pollination.  The perennial H. tuberosus is generally self incompatible and really very resistant to seed set overall so when it is used as the seed parent seed set will be low, but the seeds which are produced can be expected to be 100% hybrids as long as only one H. tuberosus clone is in bloom at a time to prevent accidental cross pollination between different clones of the same species.
  • H. tuberosus as the seed parent is fairly receptive to receiving pollen from H. annuus to produce seed whereas H. annuus typically is not receptive of pollen from H. tuberosus.  Using H. annuus as the seed parent would generally result in little to no hybrid seed being set as well as a huge waste of time growing out seedlings only to find no hybrid offspring.
 

Things can get way more complicated than this when you begin to dig deeper and the tetraploid nature of this hybrid will make it harder to select for morphological traits that you wish to pursue compared to diploid annual sunflowers on account of the higher ploidy meaning there are multiple genes competing for expression of any given trait. That said, this hybrid should still be far easier to use for breeding and selecting than pure H. tuberosus which are hexaploid as four competing genes for each trait is still simpler than six competing genes for each trait!

Below is a link to the progress I've made so far with my Helianthus breeding work (I'm not limiting myself to just these two species).  I update this blog post regularly as I gain additional information or observations to share.
https://johannsgarden.blogspot.com/2021/08/perennial-helianthus-breeding.html

Garrett Schantz

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Re: Perennial Sunflower (Helianthus) Breeding
« Reply #1 on: 2021-08-24, 02:41:40 PM »
This is all quite interesting.

Unsure of how well a large headed sunflower would work with large tubers. Being a perennial might help mitigate that issue. If the tuber develops early on and the sunflower develops later in the season that would be nice.

I know that Edgewood Nursery had a few helianthus species that I was planning on buying at some point.

Cluster Terrasol seems like an interesting one.

Johann Kuntz

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Re: Perennial Sunflower (Helianthus) Breeding
« Reply #2 on: 2021-08-24, 03:05:19 PM »
This is all quite interesting.

Unsure of how well a large headed sunflower would work with large tubers. Being a perennial might help mitigate that issue. If the tuber develops early on and the sunflower develops later in the season that would be nice.

I know that Edgewood Nursery had a few helianthus species that I was planning on buying at some point.

Cluster Terrasol seems like an interesting one.

Because the hybrid is tetraploid (4x) with only 1x being from the H. annuus parent and 3x being from the H. tuberosus parent the first generation (F1) cross will produce flowers only slightly larger than the H. tuberosus parent from which they get 75% of their genetic material.  The F2 generation is where some individuals would inherit a greater concentration of H. annuus traits if H. annuus type flowers are to be selected for.  Of course some individuals in the F2 would also be more concentrated H. tuberosus traits while yet others are more unpredictably mixed between the two with possibilities for previously uncommon genetic combinations to result in phenotypes not seen in either parent. 

Honestly even in the F1's I'm seeing greater variation than I had anticipated so the F2 generation even from the same initial lineage could be selectively culled to continue breeding for any number of traits according to what the breeder desired to pursue.  I'm working on creating numerous unique F1 crosses to further breed with and am interested in selecting F1's, F2's, F3's, etc. for separate goals.  Some I want to select for ornamental purposes and others for edible purposes with any that combine highly edible and ornamental traits being of high interest even if not the primary goal.
« Last Edit: 2021-08-24, 03:15:31 PM by Johann Kuntz »

Johann Kuntz

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Re: Perennial Sunflower (Helianthus) Breeding
« Reply #3 on: 2021-08-24, 03:14:04 PM »
This year I'm also working on crossing H. ×laetiflorus (hexaploid) with H. tuberosus (hexaploid).  Although H. ×laetiflorus produces rhizomes instead of tubers it already shares a lot of the same genes as H. tuberosus due to its anchient hybrid ancestry, but it produces seed much more readily.  My hope in crossing them is to create one or more clones that lean towards H. tuberosus tuberization traits while retaining easier seed set of H. ×laetiflorus.  Because the hybrids would not differ in ploidy from either parent they could be used as breeding material for back crossing to pure H. tuberosus with no mismatched chromosome induced sterility in the resulting offspring.

Walt

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Re: Perennial Sunflower (Helianthus) Breeding
« Reply #4 on: 2022-06-06, 02:08:21 AM »
I've used Helianthus pollen over a week old with good results.  Of course I used fresh pollen whenever possible.