David, you mention that roses generally tend to have less vigor as tetraploids compared to diploids.
I have worked some with species, but mostly with the persicas. Virtually all of the species seedlings had lots of vigor (almost too much!) With the persicas, I have spent more time and have noted that the repeat blooming ones are more compact and tidy as compared to the non-remontent ones. Also, I am finding more fertility in the repeat bloomers.
Together, the characteristics of more bloom production and greater hip set, seem to cost the plants more energy. I wonder if that is partly why the plants appear less vigorous? The non-repeat bloomers produce long green canes with lots of leaves that continue to contribute energy to the plant.
Jim Sproul
Hi Jim,
I am so excited about all the advances you are making with the persicas. That is great that you are getting some compact repeat, fertile bloomers!!! I got ‘Roses are Red’ and ‘Persian Autumn’. I have had a hard time getting them to bloom and they have that long stringy habit that people say is typical. R are R set a couple hips with one or two seeds inside each and was 3x when I counted it and P.A. is 4x and set more hips. Maybe you are beginning to break some potential linkage between the halo and that growth habit and getting the halo gene(s) into more and more of a traditional rose background. Perhaps the fertile, more rose-like hybrids may be 4x from the backcrosses to modern 4x roses if that is the ploidy of the parents you are using.
I’ve noticed a lot of hybrid vigor in many of my species crosses as well no matter their ploidy. In comparisons between diploid and tetraploid versions of the same genetic background (haploids of modern 4x roses with the 4x rose or a diploid and its induced tetraploid) the trend for a quicker growth rate (more nodes more leaves in a given period of time) in the lower ploidy seems pretty consistant. Hip set like you mention and other factors come into play for where the energy goes and new growth rate probably as well.
David