Hi all,
I’m at a point where I’m trying to come up with a way to evaluate the worth of my seedlings. One of my goals is to create (for example) a rust or russet-colored rose with a deep cup shape, many petals, and a strong fragrance. So, say I started with a cross of Edith Holden (for the color) and something with a deep cup shape and the amount of petals I’m looking for. The result is a seedling with a similar color to EH, and a few more petals, but still not as many as I was hoping for.
The question is, in this thought experiment should I throw away the seedling and start again from scratch, or would it be worth using this seedling to cross with something else to maybe get closer to my goal (so, either something with the shape/petal count I want, or something with a stronger fragrance)?
I guess what I’m trying to ask is, at what point does the risk of losing one trait of a seedling (in this case, the color of Edith Holden) outweigh the value of continuing to use the seedling in crosses in the hopes of adding another trait I want? Is it worth backcrossing with EH again at some point to reinforce the color? Or is this just way too complicated, and should I keep retrying the original cross until I get the color and shape/petal count that I’m looking for, and then proceed from there?
Any comments would be appreciated!
Thanks!!
Link: birthofarose.blogspot.com/
There’s an old rule of thumb that 100 seedlings shows the range of traits available. Approximately true. So I’d say you need to see if the color comes through in some fraction of 100 seedlings of a particular combination, if the shape and petal count come through in some, if disease resistance show in some. Then you can make an estimate of the chances of combining all the traits you want. If half have color, half have petal count, half have form, half have disease resistance, then only a very small fraction are likely to combine all these (1/16). With 10 selected traits it might be 1/1000. This is a very rough way of estimating but it gives an idea of how hard it might be by simple crossing.
Backcrossing doubles your odds of getting something like the BC parent. Very rough estimate again. But if you’re going uphill against some dominant traits from the other parent your odds may be worse than you want to think about. So the repeated backcross, with selection, lets you introgress one or few linked traits into a suitable background. So if it’s just the color you want to preserve, and all else is up for grabs, backcross to the desired parent, or intercross sibs.
For instance this year I had first bloom on a backcross of my (Carefree Beauty x Austrian COpper) onto Carefree Beauty. It maintains the color more or less of A.C., and the growth habit and foliage and once-blooming trait. But it has, so far, the disease resistance of C.B.
If you study the pedigrees of C.B., or the Knock-out roses you’ll see a lot of sib intercrosses, backcrosses, and in general line breeding to maintian the disease resistance of a few parents, with the floriferousness of HT/floribunda.
Hi Peppa,
As Larry indicates, gathering all of the desired traits into a particular rose takes many repeated crosses. If you are happy with the sampling results of 100 seedlings, and all of your desired traits are seen in the seedlings (just not together in one package), I would repeat the cross extensively. How much time and effort you put into it depends on how much you really want that rose that you are imagining. Be on the lookout though for something else that shows up that you weren’t planning on. Not infrequently, I have been pleasantly sidetracked by something that showed up that was unexpected.
As scientific as we would like to be about setting up crosses, there are many surprises - both good and bad!
Back crossing is definitely a good way to possibly concentrate desirable traits.
Jim Sproul
Larry and Jim,
Thanks for the information - what you’ve said makes a lot of sense and is the kind of insight I was looking for.
Since I have only started hybridizing roses in the last few years, I’ve generally been using the “shotgun” approach - trying as many different combinations as I can in small batches to see what I would get.
As for ‘Edith Holden,’ I crossed it with ‘Magenta’ two years ago, and with ‘Abraham Darby,’ ‘Ebb Tide,’ ‘Tom Brown,’ and a few others last year. So while I can’t speak from 100 seedlings’ worth of experience yet, it certainly seems that all of my ‘Edith Holden’ seedlings have ended up with less than twenty petals. I’m guessing that this may be the result of a hybrid musk rose with a low petal count recently in EH’s ancestry, but I’m not familiar enough with hybrid musk roses to know how strong their traits generally are.
As an example of my luck with these so far: Today, one of the ‘Abraham Darby’ x ‘Edith Holden’ seedlings flowered for the first time - the seedling has lost the rust color, has even fewer petals than EH, and has no smell whatsoever. Lovely. 
“One of my goals is to create (for example) a rust or russet-colored rose with a deep cup shape, many petals, and a strong fragrance.”
Our vision of the color that you’re describing may be different, but I think I’m wanting something very similar.
I envision a color similar to that of ‘Daily Mail Scented Rose’; which, as far as I know, isn’t available in the states. Closest thing forward would be ‘Dusky Maiden’ (which is a single) and closest thing back would be ‘Chateau de clos Vougeot’ (which has a lot of great descendants). So I was thinking something along the lines of Charles Mallerin x CdcV (or maybe the other way around). The end result which would then be applied to my KO x OK seedling
to darken the color of it and get what I’m wanting. Or at least that’s the plan… what you get and what you want are two different things.
or maybe Charles Mallerin x Brown Velvet?
I do not have a lot of experience in rose but from other plants. I would keep the nicest seedlings that have most of the traits you want and use them as breeding stock. If your original cross is PlantA x PlantB, and this cross has 6 traits spread out between the two parents. Say 3 traits each. It can save you some time if your new seedling has 4 of the 6 traits you wanted to use it in your breeding program. With many traits like have 6 distinctive traits it is easier to make improvements one generation at a time then to hope for a single cross to make the leap. Sometimes the likely hood of a single cross doing this is like winning the lotto.
Also remember some of your traits can be recessive, or they many depend on the number of copys. So your seedlings may have the genes you want but they are not expressed or they are not expressed in the level that you would like.
On petal count from what I remember you have more than one type of gene inter playing with each other. The first type determines if the flower is double or single. Double flower are dominant if I remember right. The second type of gene determines how double your double is. It does not get turned on unless you have the first type of gene.
Hybridizing is like a big ladder. Every step you make up the ladder is a step in the right direction.
Jon, your seedling looks very nice, and I’m interested to see how your potential crosses turn out!
Adam, thanks very much for the info - It’s certainly something I will keep in mind!
To follow up a bit with the “100 seedlings’ worth of experience” concept - is it worth (if I had the time, space, and/or inclination) doing 100 of a match each way? I.e., 100 ‘Edith Holden’ x ‘Abraham Darby’ and 100 ‘Abraham Darby’ x ‘Edith Holden’? (So switching which rose is the pollen parent and which is the seed parent?) I know this is a whole other can of worms, but is the general consensus that you’ll get the same traits from a match regardless of which rose is the seed parent and which is the pollen, or are there potentially different traits (or different percentage chances of getting those traits) that could arise? Just curious… 
Thanks!
As far as the direction of the cross matters the genes should not matter which way the cross takes place. However mitochondria DNA and some other cell organelles are inherited through the female line. I think this is why it is said some parents produce weak seedlings as female parents but when they are used as male parents the seedlings seem fine. I think in these seedlings they may get weak chloroplast or something else in the cell functionality. But this is not studied at all that I know of in roses. So my thoughts may not be totally right. Last year I did make crosses involving Angel Face and the resulting seedlings where far more vigorous as a pollen parent then as a female. A lot of the seedlings had reciprocal crosses. But I did not do in the number to make a real connection with the data. By the way none of these seedlings where worth keeping even the vigorous ones.
I have read it several times in the literature regarding smoothness ( few or no prickles) from rose breeders that in a cross, it is best to use the smooth parent as the female. I don’t know if studies had been done or if this was just the observation of the hybridizer.
Jim P.
Hi Peppa,
Though theoretically there may be differences, I think for the most part they are small. I think the best direction to make your crosses is in the direction of the best seed parent. Efficiency is key with the most limited resource - time.
Jim Sproul
I have used My Stars a lot and it sets seed galore but almost 0 germination. Its pollen on the other hand sets with almost all seed setters and the resulant seedlings are almost all thornless. Therefore I agree with Jim about using the best seed parent.
Patrick
Hi everybody,
Thanks so much for the input! I find the thornless theory very interesting, as I’m not a huge fan of thorns to begin with…
Efficiency is key with the most limited resource - time.
Jim, that completely makes sense. If only we all had the time/square footage to explore as many options as we would like.
I do also agree that, however small, there are probably some differences between using one rose as a pollen parent or as a seed parent. For example, I have heard from Japanese hellebore breeders that the incidence of double flowers in hellebores depends very much on which parent is the seed and which is the pollen, and reversing them drastically reduces the liklihood of doubling. (I’m guessing this has to do with the gene in hellebores for doubling being recessive, perhaps? So that it is much more likely to be passed along by the pollen parent as opposed to the seed…?)
Of course it also seems to be the case that, no matter how prolific a specific rose pollen or seed parent might generally be, there are certain combinations that, for no obvious reason, just don’t work for me. It seems to me that this would support the idea of some form of inherent incompatibility between some roses (or their genes), yes? Or maybe some roses just don’t get along, as it were. Or, maybe more likely, my pollen was a little old, or there were some environmental factors that contributed.
Thanks again for all your comments!
Peppa,
The test of whether or not a particular rose makes a good pollen parent, is to use fresh pollen. That is, pollen from anthers that were collected the day before pollinations.
Regarding time and space, as you know, Mr. Moore was extremely innovative and brought lots of excitement into roses, however, even though his career spanned more years than most of us on the forum have been alive, he still had many unfulfilled goals.
Something that I am trying to do, but still find very difficult, is to concentrate my efforts in fewer directions. There is so much to explore in roses…
Jim Sproul
With diploid roses, there is definitely self-incompatibility, as there is in apples or pears. Also, any two plants might just happen to express the same combination of incompatilibities through some common descent.
Then there is imprinting, where one parent or the other activates or inactivates certain sets of genes.
Then there is linkage disequilibrium, whereby certain clusters of traits stick together, even though they are encoded on different chromosomes. For instance species crossed onto HT often end up looking very much like the species in many ways, even though it only contributes half the genes to a cross.
I think I’ve written some articles in the RHA newsletter about these effects, at the molecular level.
So all in all, for wide crosses especially, the rules about seeing traits in say 100 seedlings, are very rough indeed.
I use a test cross to a very accepting parent such as Carefree Beauty, or a special seedling of it, to see whether pollen is good- but of course that takes at least a couple weeks to know. But it might alert you for next year. Similarly, using a very good pollen donor you can get a feel for whether a parent is likely to accept pollen well. But neither test if foolproof, for the obvious reasons mentioned.
Your definitely right about the temptation of getting side tracked. From my own observations added with all the great insights others bring up on the forum or in the journal it is hard to stay on a clearly defined path. I notice things all the time I want to do. Too bad I do not have thousands of years to experiment. Right now I am working on 3 programs and try not to do anything unless it will add to one of these programs. Luckly I do not have a lot of room for roses so lack of genetic material helps me from being distracted as much.
Peppa one cross you might want to try is Edith Holden x Hawkeye Belle if you have Hawkeye Belle.
Thanks for all the info!
Jim, I was just curious: In your experience, how long do you find pollen to be viable after collection? I understand that it’s best to use asap (ideally the next day), but the flowers don’t always cooperate. Do you notice a substantial drop in success rates after two, three, four days? What do you think about refrigerating pollen?
Larry, great info, thanks! I really like your idea of a test cross - I think I will be trying that in the future.
Adam, thanks for the reco! I don’t actually grow Hawkeye Belle, although it’s quite pretty. Have you used it in crosses before? How does it respond?
Thanks again!
I will use pollen for at least a week after the collecting date, assuming daytime ambient temps have not risen above 85F. In that case, I may limit myself to five days. Unless it is left somewhere excessively hot, I find pollen remains viable for a rather long time. If you need it for a cross that won’t be possible for more than ten days out, then freeze it in an airtight container once it has dried thoroughly: 2 days at least.
Regards,
Paul B
I have not used it myself. But I remember reading in the RHA journal that it almost always produce doubles and many of these have many petals. The parentage is good behind this one. Coming from Buck it can not be too bad. I think with the parentage behind it. You have a very good change of installing hardiness, cupped flowers and possible disease resistance. Color however might be hard to get in the first generation as it ancestors are heavy on pink. But you could use it as a stepping stone for what you want. I am planning to get it myself in the near future. I think that it could hold some possibilities. Any one who has used it do you think my theory on this one is worth trying?
Peppa, for me in my climate, pollen fertility is significantly shortened as compared to Paul’s experience. Pollen fertility drops off significantly after 3 days here, which is why I try to use pollen that is only 1 or 2 days old. That way, I get very good hip set. Our climate is warm and dry outside, and the pollens that I use are exposed to the hot/humid greenhouse conditions intermittently. So, maybe those extremes result in quicker loss of viability in pollens here.
Jim Sproul