A number of forum posts have had to do with ploidy in roses, something that I would like to understand better. I understand from both roses and other flowers that higher ploidy levels are thought to lead to larger and/or “stiffer” flowers. However I do not know how consistent this relationship/correlation is. I have a few related questions along the lines of this general topic.
My understanding is that in some cases different ploidy levels exist in the same species. In those cases, will roses of the same species exhibit any notable difference in flower size/form based only upon their different ploidy levels?
Along the same line, when diploid roses have their chromosomes doubled artificially, does their flower size/structure change in any notable way? For example, I have an artificially doubled rose (from wichurana x banksiae). Since I only have the doubled form, I cannot compare it to the original. But if I could, would the flowers have any notable difference in size/form?
I think of certain classes of roses having “general” ploidy levels associated with them. For instance, I think of polyantha roses and many ramblers as being generally diploid (although I expect that there are some exceptions) and generally also having small flowers. In these classes is the correlation between flower size and ploidy because of diploid roses generally having smaller flowers, or is the correlation merely an artifact from those classes’ ancestries (in many cases involving diploid R. multiflora and/or diploid R. wichurana)?
In a contrasting example, I think of hybrid teas as generally being tetraploid, although again I understand that there are exceptions. Again, is there something about higher ploidy level (i.e. tetraploid) that is necessary for the form of hybrid teas (with their thicker petals and upright stems), or is the correlation between their ploidy and plant form simply an artifact of the ancestry of the hybrid tea class?
I once read someone suggesting that fertile triploids could be used as a bridge to bring traits from tetraploid roses to the diploid level, or vice versa. If the general ploidy levels of different rose classes are mostly an artifact of each class’ ancestry (and not inherently necessary for that class’ form), then this seems reasonable. If there is something inherent to the ploidy level that makes the characteristics of that class possible, then that suggestion might not be reasonable. For instance, could hybrid tea form actually be brought into diploid roses, or does the ploidy level of hybrid teas do something important in making hybrid teas’ form possible?
This is a topic I’ve been interested in…thanks in advance for any helpful thoughts.