In 1986 P. Cole and B. Melton published a paper which investigated the ability of species rose pollen to fertilize flowers on the same bush (Cole, P., Melton, B., J. Amer. Soc. Hort. Sci., volumn 111, pages 122-125, (1986)). The diploid species were all highly self steile. None of the 23 diploid specimens exhibited over 4 % fertility and 18 of the 23 produced no self-set seed. They also studied the fertility with pollen from another plant of the same species and found that the diploid group was 50 times more cross compatable than self compatable. For roses of higher polyploid level 12 of the 16 studied were no more self compatible than the diploid group.
Has anyone noticed this behavior in their own species roses?
This is of interest to me as one virus transmission study tested the seeds and seedlings of infected species roses that had a non infected species rose next to it (the non infected bush was put there for a bush to bush transmission study). It would appear to me that he should of been testing the seeds and seedlings of the non infected neighbor if the roses could not self pollinate.
Thanks for sharing that information. It’s particularly interesting to me, because I’ve twice now gotten branches on sterile diploid hybrids that I’m almost positive were converted to amphidiploidy (using trifluralin). One has died; the other is doing well. I had figured that self-pollination of flowers on these branches would produce seed, thereby confirming the conversion. The deceased branch had three flowers before I lost it, and none of them would set selfed seed in spite of the obviously larger thicker anthers (and petals, leaves etc.) Last year I tried selfing the newer converted plant; once again there were no seeds. I had thought of several possible explanations for the lack of seed set. Now it looks pretty certain that the self-incompatibility theory is most likely. So this season, I’ll have to definitely try out other tetraploid pollen on flowers of the probable converted plant.
Tom, in all fairness to the RHA, I should point out that Cole also published a version of the article in the Rose Hybridizers Newsletter. I cannot state the actual issue as at that time I was removing the articles and placing them in the corresponding topic folders.