According to Hurst, the early albas are all hexaploids that produce tetraploid eggs and diploid pollen. The theory is that the later albas, which are tetraploid, are the result of crosses between tetraploid old roses and alba pollen. One of the early albas (maybe the first in cultivation) is ‘Semi-Plena.’ I wanted to use it as a pollen parent last year, but I had really bad luck: I think that I got exactly one seed. Semi-Plena is undoubtedly very fertile relative to OP seed, and I’ve had good luck with gallica pollen. Does anybody have any experience with breeding this, or similar roses?
Why not use it as a pod parent as I did? I did a few crosses it already using the little amount of Compte de Chambord’s pollen I had yesterday. I saved the ASP’s pollen in a small vial so that latter I can pollinated it with my Mme. Isaac Periere, which sets hips only latter in the season in my case. Last season I did make a few pollinations using pollen from English Roses, non of which has sprouted this year. My Kazanlik is giving bloom now, I’m going to use alba Semi-Plena with it this year aswell as I love the old damask alba hybrids and think that there should be more out there. I think their was a thread on the older fourm which you may find intresting. I lost the link, but a search may yield you the older site.
I have read that the process of Caninae-type meiosis produces a large amount of un-viable pollen. Despite this, most of the Caninae section roses set lots of OP hips. I wonder if you are runing into a simular problem?
If you are interested, I will try to find a copy of the article.
Joan, I believe that I have the article that you mention. If I remember correctly, one of the main things that they looked at was apomixis. Thanks for reminding me about the low pollen fertility issue. Presumably, the plants self-pollinate due to large amounts of pollen compensating for poor quality. I think that I will try using more pollen, and over more than one day. I don’t usually bother with pollinating more than one time, but this sounds like a good time to make an exception.
I avoided using any of the albas or canina as females because I would like the offspring to be tetraploid so that they can be bred with modern roses easily. If I use albas or canina as the females, the offspring will presumably be hexaploid. I have been considering such crosses with R. eglantera, however.