Has anyone ever done any test on seed size?
In some crosses the seeds differ very much in size. I always do a float test, and still I am left seed that are half, or a third, of the size of the other seeds from the same cross.
I always plant them out anyway, but i have never been disciplined enough to test is s small seed will germinate as well as the big seeds.
Has anyone done any test on this subject or do you discard very small seeds?
This last season I let all my seeds germinate in the fridge and potted them up as they germinated.
I had kept some small seeds (compared to others in the same hip). These were not tiny, but we’re half or a bit less than the larger seeds. I did not keep track of percentage of small germinating verses large, perhaps I should have. But I definitely had small seeds germinate.
This was not in every case. It probably would have been helpful to record which seed parents had small seeds germinate and which did not, as some definitely did not germinate small seeds.
It would be an interesting study. I am wondering, however, if it would vary greatly with different cultivars.
Duane
It depends upon the genetics. Nessie, [(R. Brunonii X R. Gigantea) X Mlle Cecile Brunner] is a cathedral eater, yet her seeds are TINY and they all germinate. I have offspring from her with Mlle de Sombreuil (George Washington Richardson), Faith Whittlesey, Purezza and even Tom Thumb! Golden Angel is a triploid mini which produces HUGE seeds, about as large as some of the Teas, and they all germinate, too. 0-47-19, Ralph Moore’s Wichurana X Floradora, makes the tiniest seeds and they all germinate. Nessie’s pollen on other seed parents produces varying seed sizes and so far, I’ve not encountered any apparent difference in germination between the sizes. I plant a dozen seeds and I get a dozen seedlings.
From the studies I have read (and there may be contradictory studies), seed size is relative to mean seedling vigor relative to the parent’s sizes, but not ploidy.
The parentage of ‘Fraņcois Juranville’ is Rosa wichuraiana × Madame Laurette Messimy, the latter is a repeat-blooming Hybrid China. So the KSN loci genotype which controls blooming habit of FJ should be KSN/ksn, and the phenotype is once-blooming (repeat-blooming is recessive). If your FJ is pollenated by a repeat blooming rose, half of the seedlings are repeat-blooming (ksn/ksn) and the other half are once-blooming (KSN/ksn). That’s a typical Mendel segration.
