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The last article I wrote for this series on my daylily breeding program dealt with F1 base plants from the Four Bases, the primary layer of my program, that have gone on to become introductions and primary breeders in my program. In that article I described the Foundational Tetraploid Introductions of my program, with a focus on Sun Dragon and Korean Queen, and the role they play in the development of my program. In this post I will look at the next layer of introductions from my program - the Secondary Layer. We will touch on some important plants at this level, introductions I have made at this level of my program. Click on any of the linked subjects above to read about that aspect of my program.
The secondary layer of my program is composed of hybrid, domestic tetraploid daylily cultivars. It is based 100% in the work of flower breeders, who have given us amazing lineages of daylily flowers, all stemming from the foundational work of A. B. Stout. My love for the beautiful flower genetics of the modern daylilies meant that I could not start strictly from species and near-species-like cultivars. Even though I knew I would inevitably produce flowers in the early generations of my program superficially similar to the Stout cultivars, I did not want to start with the handicap of having to remake the fancy flower genetics from scratch.
I knew I had to incorporate those advanced flower genes from the fancy gene pool, and by using such plants, that gave me a tremendous leg-up on Stout in terms of genetic potential. My early outcrosses are all saturated with recessive (and some co-dominant or low-penetrant-dominant) fancy flower genes. In order to do this, I had to ensure from the get-go that I had a sound base of modern flower genetics to cross into those species-like base plants to create lines advanced in both plant and flower traits.
While there is not a massive phenotypic range of plant traits in the domestic tetraploid gene pool, unlike its flower genetic variations, that gene pool shows a bell curve from a tiny number of plants showing exceptional traits to a large middle ground of moderate or adequate traits - we’ll call them ‘average', to the other end of the bell curve - highly undesirable traits. The key was to isolate plants that are on the upper end of the possible spectrum for desirable plant traits within the very bottle-necked tetraploid hybrid gene pool, with enough fertility to be viable, and that were low enough in recessive, hidden deleterious traits to be backcrossed to in the future. It takes time to make such determinations. As well, from the start I was on the outlook for any fancy moderns that broke the upper end of the bell curve spectrum and showed an exceptional plant trait, such as pod fertility/seedling viability, exceptional rust resistance/breeding value, thrips resistance/breeding value, vigor, height, branching, etc. (You can read about the secondary level introductions from other programs that I have focused on in establishing my program here, Secondary Layer.)
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To do that, I brought in many fancy cultivars and tested them through the foundational period of my program, during the first ten years from 2011 through 2021. My criterion was to find fancy domestic cultivars that were good enough growers and breeders to be worth permanently maintaining and even potentially being backcrossed to, or inbred with, at some future point in my program. This is the main criterion for the secondary layer of my program: a plant I would not be afraid to inbreed with or to backcross to in the future.
I also used quite a number of other cultivars in experimental breeding, and some of them even contributed genes that I am still trialing out, but I would not trust backcrossing to them or inbreeding with them. They compromise the Tertiary Layer of my program - plants good enough, or with unusual or very desirable flower traits, to use once, but not good enough to go back to for backcrossing and absolutely not to be used for inbreeding.
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The program then falls into three categories: foundational base plants - species or species-like, secondary hybrid cultivars, and tertiary hybrid cultivars. At the foundation of my program, the species and species-like base plants were being crossed to either secondary or tertiary plants. In the early years of establishing a program, there was no way to know yet if a given cultivar was going to end up being secondary, tertiary, or not used entirely.
I quickly came to understand that crossing plants from the secondary or tertiary level with each other often produced less vigorous and more genetically similar results. I.e., while flower variation was high in some instances, plant traits were fairly uniformly locked into narrow parameters, so that there was little opportunity to select for resistance to thrips, for instance. The same was true with rust resistance and other important and desirable plant traits.
The plants deriving from crosses of the four species/species-like base plants to either secondary or tertiary plants all showed greater genetic diversity for a range of plant traits, and were infused with fancy, modern flower genetics to boot, creating the genetic background from which more genetically diverse plants with fancy flower traits can be generated and segregated. However, it requires genetic diversity to make such selections. In the species/species-like base plants, there was little genetic diversity for flower traits - for instance, none of them show or carry genes for purple coloring. While in the fancy flowered hybrids, there was little genetic diversity for natural fertility, high vigor, and a host of other desirable plant traits.
While there may be a handful of examples that show one such trait exceptional and above even the high end of the spectrum, it is extremely rare to find a modern, hybrid cultivar that shows multiple important plant traits in the exceptional level all combined into one plant. That is what the most important of the secondary hybrid cultivars I selected showed - a higher than average number of, and expression of, desirable plant traits in combination with a modern, fancy flower. I can say that the best of all the secondary cultivars that I have tested, which shows the greatest number of desirable traits on one plant, is Solaris Symmetry.
To date, Solaris Symmetry is the only fancy, modern hybrid from someone else’s program that I have successfully backcrossed to repeatedly and used in tight inbreeding, including selfing. I have tried these techniques with many other fancy, modern hybrids, but have uncovered a large number of undesirable and/or deleterious factors lurking in their genes, and so those plants were eliminated from full secondary status consideration, some becoming the low end of secondary (where they were still above average, but not exceptional) and others becoming tertiary level, while some were eliminated from consideration entirely.
I current still have a small handful of hybrid cultivars from other people’s programs that are in the final stages of testing to potentially join Solaris Symmetry in its vaunted position within my program. The key to understanding my focus on Solaris Symmetry is that it shows far above average, exceptional thrips resistance, in addition to having multiple other desirable plant traits. (Read more about Solaris Symmetry here.)
However, out of my own breeding work has come introductions that are crosses of secondary hybrid cultivars from other programs, or crosses of secondary and tertiary hybrid cultivars from other programs, that are entering the secondary level, some remaining important for their fancy flower traits on strong, selected plants but not gaining full secondary level status like Solaris Symmetry, while others are potentially moving into the high status of Solaris Symmetry. Many of these will end up being maintained and utilized in my program for years to come, and are foundational to it.
These plants do not descend from any of the Four Bases, and so do not carry the outcrossed, species/species-like genetics. They are fully a part of the standard, hybrid tetraploid daylily gene pool, but represent those that have been the best performers in my garden. My goal in generating these plants was to create a base of hybrid genetics that represented the high end of the spectrum in terms of plant traits and flower traits, or exceptional instances exceeding it, that could be used to outcross to the Four Bases or to F1 Selected Seedlings/Introductions. While these plants are screened for traits like rust resistance and thrips resistance, they have not been bred specifically for either, because they were coming strictly from the fairly random and narrow gene pool of the tetraploid hybrids.
It is important to understand the distinction between applied selection through screening and through actually breeding for specific traits. In the first example, screening for resistance, whether to pests, pathogens or other traits, one is taking a random sample of plants and selecting for a set number of traits. In this phase, I was looking for the high end of the spectrum for desired traits, while staying alert to recognize exceptional individuals that greatly exceeded the high end of the average spectrum. While such plants may then also prove to have breeding value for their expressed trait, they also may not. Screening doesn’t guarantee exceptional plants. What it does is identify the full spectrum of phenotypes expressed within a given gene pool.
Resistance breeding, or breeding for select traits is a different endeavor. In this practice you are seeking to establish breeding value for traits, and to then amplify those signals within the genome, which in turn creates a higher number of desired specimens. As well, selective breeding can allow for the concentration of exceptional traits, rare and hard to find in the average gene pool, while also allowing for the pyramiding of genes and other modification factors that can intensify the frequency and penetrance of a given trait within a population.
Now in common English, this means that the standard tetraploid gene pool, even at its best, has limitations, an upward ceiling that is very difficult to break, due to the intense inbreeding and subsequent genetic bottleneck of these lines. It also means that the best plants from screening the standard tetraploid lines for desirable traits like thrips resistance or plant vigor may not be much more than average. In thrips resistance for instance, almost no daylilies show any resistance to thrips, so even the high end of the average expression is not spectacular, as it is in the exceptional individual Solaris Symmetry or some of its descendants and relatives. Other daylilies without this lineage in them, even when showing higher than average resistance, still may not be really all that resistant and will still show considerable thrips interaction, especially in the early part of the season or when the conditions become very dry.
Most of my secondary introductions, which can be assessed by the fact that they lack Solaris Symmetry and one of the Species/species-like four base cultivars in their ancestry, will show slightly above average expression of a wide range of traits, but will not far exceed the average high end, because they do not have the genetic heritage that would allow that. They were screened for resistance, but are not bred for resistance, because they derive from the standard gene pool of hybrids.
Those bred from 2011 through 2015 were screened for rust resistance. Thrips resistance screening began in earnest in 2013 and continues on to this day. Those bred from 2015 through approximately 2020 have only been screened for thrips resistance, as my rust screening had concluded by that time, but they will generally not be exceptional for thrips resistance, because they are the foundation of selection that, through combining them with exceptionally thrips resistant lines like Solaris Symmetry, can go on to produce lines of fancier flowers on robust plants with species/species-like ancestry and exceptional traits derived from the tiny handful of exceptional ancestors that are the foundation of my program. Many plants produced after 2019 will have higher thrips resistance, because it was in 2019 that I was able to finally start crossing proven breeders for high thrips resistance.
Many of the secondary cultivars in my program are excellent plants, but will not be cutting edge on every trait. In my program, they serve as a reservoir of fancy flower genetics, combined with the best plant traits I could A) find in their ancestors, and B) select through screening the seedlings. It is only now, over a decade into my program that I am beginning to make the breeding strides combining the four bases and the best secondary and tertiary lines. I am past the point of just trying to find anything to breed and combine with the tiny number of exceptional plants I had identified. I am now reaching the point where I am beginning to establish lines that incorporate the best traits of my F1 Introductions from the Four Bases and the best secondary introductions coming from the best of the secondary and tertiary crosses I screened through the first decade of my program.
These Secondary Introductions represent my screening work, but they are not really fully representative of my breeding, because they are often only a generation or two removed from other people’s programs, and so are not far enough removed, or infused with the genetics of the Four Bases, to really be something very different from the standard hybrid tetraploid gene pool. They are a tool within my program, required to reach my final goals, and I make many of them available to other growers through introduction as they are often excellent garden plants, breeders and as good as most other daylily from the standard tetraploid gene pool, and in some instance, better in one or more important traits.
Here is a listing of my tetraploid introductions to date (2024) that I consider to comprise the secondary level of my introductions (ordered by date of introduction).
Elizabethan Courtly Love, Elizabethan Sharp Wit, Glow Of The Heart, Solar Disk, Arrowhead Star, Bela’s Star, Dragon Princess, Elizabethan Persistence, Flaming Candelabra, I See Your Teeth, Substance Upon Substance, Black Hole Sun, Elizabethan Fairy Queen, Elizabethan Lace Collar, Elizabethan Royalty, Explosion Of Substance, Solar Soul, Welded Dragon, Elizabethan Argus, Elizabethan Fine Gloves , Elizabethan Minerva, Elizabethan Rainbow Portrait, Emerald Trader, Little Dragon On The Prairie, Elizabethan Fantasia
