Late onset recurrence versus juvenile recurrence

General Discussion
1

These two types of reblooming were mentioned recently in this forum and I would like to learn more about this topic.

Until now I only knew recurrence as being transmitted by a recessive gene. But there is apparentely more to it, with other genes that confer some “late onset recurrence”, that seems to be harder to understand (polygenic? interactions between several genes?)

Lots of questions arise:



Is juvenile recurrence the sort of reblooming inherited by simple recessive inheritance?

At which age of a seedling does late onset recurrence appear ?

Is the blooming performance of mature plants the same in both types of recurrence?

I wonder what sort of recurrence Louise Odier has. I have two plants of 10 years age and by now both plants have flowers all summer. In their first 3 years there was a nice first flush of flowers, but after this the plant in better position had only scattered blooms, while no 2 which had to put up with more competition was completely once flowering.

In 2007 I had 40 op seedlings of LO, 8 of them had flowers in the first season. They looked all very similar, so I assume most of them were selves. The surounding offers lots of other potential sources of pollen, but all of them recurrent. So I thought all seedlings must have 4 copies of the recessive recurrence genes and was dissapointed by the low number of flowering seedlings. In 2008 year I had 3 additional seedlings blooming for the first time from those seedlings of 2007. But there was no recurrence in the latter. And there are still some small seedlings from 07 that have not produced any flower.

Can anyone explain these observations?

Looking forward to your answers

Ulrike

2

A lot has been written about recurrence on this forum. A search may pull up more than you want! Briefly:

Juvenile Recurrence means the first bloom is formed very soon after germination, and bloom continues (at least in cycles) any time after that that conditions are favorable. Generally, the first bud is visible about two months after germination, but I used a four-month cut-off for my research on the subject, to provide a margin of error. Most modern roses have juvenile recurrence, and the trait comes from China/tea roses and other sources. The trait is recessive, making it difficult to recover when species are crossed with modern roses. Juvenile recurrence can be suppressed, presumably by additional genes. An example is R. rugosa seedlings, which become recurrent after a year or so. Climbers also represent some kind of compromise between recurrent bloom and stronger growth.

The term late-onset recurrence is less well defined, and roses that are said to rebloom when mature can have many different reasons for doing so, I expect. Many simply will have a few late blooms when conditions are favorable, and are not recurrent at all. The clearest example of late-onset recurrence I can think of is the form that comes from R. laxa, and is found in many hardy rose hybrids. It is not controlled by the same gene as juvenile-onset recurrence. David Zlesak has suggested that this form of recurrence may be at least partly dominant, and I think he is probably correct (that is not intended to meant that only one gene is involved). Good examples of this form of recurrence seem to include