Of the roses you mentioned, I would recommend Prairie Joy and Frontenac as the ones to work with. Even though PJ is a triploid it does set seed readily and they germinate quite well. I’ve only grown OP seeds of it but Julie has worked with it a lot and it’s one of her favorite roses. Frontenac doesn’t set many hips so I haven’t bothered using it as a seed parent, but it is one of my most potent pollen parents. It is quite healthy here and reliably hardy though it’s so small it’s usually covered in snow every winter. Some of my most healthy and hardy seedlings have Frontenac as the pollen parent. Champlain is a bust, it’s not that healthy and it’s not very fertile either way. I tried it’s pollen on 6 different plants last year and it only took on two of them, one of those I only got 18 seeds. I did have good luck with it on Tuscany Superb and have 20 seedlings from that cross. Morden Centennial is fertile but it has become so disease prone here that I’m culling it this spring. Of the many seedlings I’ve grown of it I’ve only kept one so far and I’ll probably cull that this year also. Therese Bugnet is probably best used as the pollen parent and only with something that is very healthy as it’s not that healthy itself.
It s important to know that rebloom inheritance is nonmendelian in roses. Many reputable and data of my crosses of 200 seedlings show that the recover of rebloom by backcrossing is 1:8. Not 1:2.
If I recall correctly, Robert Erskine told me he was never able to get ‘Prairie Peace’ seeds to germinate. However, a friend of mine living in Edmonton has done so. I’m growing the dozen or so seedlings in Saskatchewan and some may bloom this year. They are quite uniform in appearance and therefore may have been selfed. It will be interesting to see the range of colours in them.
One more thing I want to mention. It’s good to know about the lack of disease resistance of many of the Parkland and Explorer cultivars in warmer climates than the Canadian Prairies. However, with mainly the exception of ‘Morden Fireglow’ (very prone to blackspot) they generally do just fine in this geographical region (mulching to provide winter protection is especially helpful for the former). After all, they were developed for cold climates like this one. Therefore, if a breeder is focusing on developing roses for this area I certainly would (and do) use cultivars of these two series.
If Johannes is right about the non-Mendelian nature of reblooming genetics, then the recovery of rebloom from a selfed tetraploid cross could be a LOT lower than 2.77%. That would push it from worth trying to not worth the effort. Does anybody have any real world data on such a cross?
The main difference between diploids and tetraploids is that diploids are for the most part self incompatible. A back cross of a diploid to one of its parents or even a cross to a sibling or a half sibling will have a significant number of pollinations abort for self incompatibility reasons. And that is why you will not see the pure Mendelian numbers with these types of crosses. Tetraploids for the most part are self compatible and this should not be an issue with them, so I suspect their numbers would be much closer to the Mendelian ideal, but that’s just my opinion I don’t have any real world data to back that up.
I grew some OP seedlings from one of my R.arkansana hybrids a number of years ago, but not that many and I don’t recall seeing any repeat bloom from them. I grew more OP seedlings last year from both of the R.arkansana hybrids and they haven’t bloomed yet so I can’t say if any of these have repeat bloom. Both of these plants have proven to be hard to work with, both as a seed parent and as the pollen parent so I haven’t gotten many seedlings from either of them. So far none of the second generation seedlings have had repeat bloom even in crosses with repeat blooming plants. But I have gotten repeat blooming seedlings from several of these second generation plants though. So it’s taken me two more generations to get repeat bloom from these first generation hybrids. The number of seedlings have been too low to say for certain if they are following Mendelian genetics or not.
I don’t think we can make any assertions about diploids being self incompatible, though I’ve heard it said a by a number of people. But as someone who works almost exclusively at the diploid level, I have to say that my experience has been that most diploids, including species are perfectly self compatible. I cant recall any occasion where I’ve had difficulty selfing, or sibling crossing the roses I’ve worked with.
I don’t say that there aren’t species with self incompatibility mechanisms, but I’ve seen no evidence to suggest that diploids are self incompatible across the board.
Paul, Rosa arkansana is not like a traditional rebloomer. It will bloom in Aug if cut down flush with the ground in spring and the bloom is less than spectacular. Are these hybrids that you speak like Assinaboine or are they your own crosses? What ploidy do you consider your R. arkansana. The early hybrids using this species are often triploids Cuthbert Grant, Adeleide Hoodless. This also changes the “odds”.
The R.arkansana hybrids are ones that David Z grew. He collected several R.arkansana from around the state and brought them back home. He grew OP seeds from them and kept several of them, he thinks they are crosses with descendants of Carefree Beauty. He must have had some seedlings of CB growing near them. Anyway both that I have are pink singles that look very similar in growth and blossom, but not really like Assiniboine. I’ve never measured the pollen but I’ve always assumed they were tetraploid. David may have told me that they were tetraploid and that’s why I thought that, but if he had mentioned that they were triploid I would have remembered that.
Graham,
When you say you selfed a species, do you mean you put its own pollen back onto itself? Back crosses are possible and so are sibling crosses with diploids, I’ve done half sibling crosses myself. But if you’re like me then you put way more pollen on the stigmas than is necessary to pollinate them. And if half of that pollen wasn’t compatible with the mother plant, then the only way I’d know that would be by what the seedlings looked like. This is how it was explained to me by someone who is a lot more knowledgeable about this than I am, David Z. He explained that there is a gene for self incompatibility and if the pollen grain has the same allele as either of the ones the mother has then that fertilization will fail. We had a discussion about this three or four years ago but we can’t go back that far in the searches any more.
I pollinated them with their own pollen. I’ve traded seed with a people who wanted the pure species, so I selfed the plants I’ve had to provide them with pure seed. I’ve also had a few species that flower when no other roses are in bloom produce seed. As I say, I’m not disputing that there are species with self incompatibility mechanisms, but I’ve seen no evidence to suggest that it’s true of all diploids. Also, the quantity of pollen applied would make no difference. Plants with self incompatibility mechanisms won’t pollinate themselves.
From what I’ve seen, I’d think it’s unlikely that self incompatibility would be the reason for 1:8 ratios in recovering repeat flowering. It would be more likely that repeat flowering is a quantitative trait.
It looks like you’ve proven that theory wrong, I can’t argue against the evidence. I have never done any studies myself to prove or disprove it but have relied on what others have told me. I was going to do diploid crosses this year anyway so I think I will do just like you did and pollinate some of them with their own pollen and see what kind of seed set I get. It looks like Henry has posted a link to a study about Rose compatibility, I guess I should read it.
I just can’t think of any way that a 1 in 8 ratio would happen when you back cross a first generation hybrid back to the repeat blooming parent. Even if two genes controlled repeat bloom (most people think it’s only one gene) and both of them were recessive it still should have a ratio of 1 in 4. There has to be something else causing the lack of repeat bloom in those seedlings.
May I ask which search engine you used? When I was staff at the local university I could use Agricola at the library to my hearts content. But now that I have left I can t even look up a book. all this occurred because of copyright laws and the library is forced to maintain them. And forget a photocopy. Don t know if the laws are as stringent as in Canada. Johannes
If I understand correctly, (some of the terminology is beyond me) it would appear that the researchers attribute repeat flowering in roses to a single mutation. However climbing sports of repeat flowering roses (resulting from a reversion of the mutation) having some repeat flowering, would suggest to me that there are other factors involved.
A 1:8 ratio in recovering repeat suggest that 3 genes are involved. Or that somehow preferential pairing or embryo mortality is skewing the results. I think we need more research into repeat flowering inheritance to explain what is going on here.
When I look at the entire spectrum of repeat flowering roses, as if it was a giant algorhythm, or diadic, then the information would definitely be an incomplete conversation. In other words, there is definitely missing information, and I do not see how a singularity (cause/effect), would be solely responsible.
Roses have gametic self-incompatibility and that system can be a little “leaky”. I have had diploid polyanthas that do not set op seed in the greenhouse most of the year, but do during the very hot summer months. Saving and planting that seed, the characteristics were consistent with self fertilization (a thornless parent produced all thornless seedlings- a recessive trait, so the neighboring thorny poly in the greenhouse that is likely homozygous dominant for the trait and in crosses only gives 100% thorny seedlings therefore is not likely to be the dad).
I suspect climate strongly plays a factor outdoors too. Heat can denature proteins and let self fertilization occur and some roses seem to be more prone to having SI break down. For instance, Cherry Pie is a diploid and here in MN the relatively rare op hips I get on it in my garden seem to be outcrosses from what the seedlings look like. Last fall when I was in a warmer climate I saw some plants covered with hips and collected some and have a few hundred seedlings coming into bloom now. They are all single (that is a recessive trait) and other growth characteristics are consistent with the seedlings being selfs.
I think it is difficult for us to view SI as a total yes or no sort of thing, but recognize there is a continuum of expression among roses. I’m glad I live in a cooler climate where SI seems to express more readily so on especially the diploid roses in my garden there is a stronger tendency for ops to be outcrosses. That encourages me to raise ops!!
I suspect climate strongly plays a factor outdoors too. Heat can denature proteins and let self fertilization occur and some roses seem to be more prone to having SI break down.[/quote]
Could the same be true for roses that typically don’t set many hips from foreign pollen? Could heat allow for some acceptance of foreign pollen in a similar way that SI breaks down? Thank you!
I think it’s more accurate to say that some roses have self incompatibility. The first paper Henry posted a link to demonstrates that fact quite clearly. I don’t doubt your observations, but I do think we should avoid making sweeping comments about the reproductive mechanisms at play without adequate research to support such comments.
Heat also inhibits fertilization from any pollen. Iceberg will NOT set hips in the inland hot areas here. Grow it in cooler, more coastal areas where there is more humidity and far less heat and it resembles a fruit plant. Mermaid performs similarly, though it sets far fewer actual seeds, but you do find hips. Some, such as Rosarium Uetersen, actually eliminate all sexual parts in high heat, where cool, damp conditions yeild far fewer petals and generous sexual parts.