Progress in breeding fertile AG intersectional hybrids

Don, hope this plant blooms with good flowers, which have fertility.  If you remember your visit in 2016, I have a plant of 'Bartzella' x AGLH Seedling growing here.   It has very heavy foliage which is attractive, but is a shy bloomer with small flowers which resemble P. delavayi in size.   Flowers are usually hidden in the foliage.  This plant has been kept more as a curiosity and perhaps something we could use for hybridizing.   Unfortunately, no positive results using pollen (which is produced in small amounts) or seed to date.  

Roberto, Thanks for your question. Yes, the pollen parent for my RIBC seedling was the Advanced Generation Herbaceous Hybrid (AGHH), Lemon Chiffon, just like the successful crosses made by Hans Maschke, only in my case the seed parent was an unregistered intersectional hybrid (R8P9) of my own breeding, which I refer to by its garden name "Mother Superior". This rare i-hybrid is by far my best and most reliable seed-setter, among all of the hundreds of intersectional hybrids in my garden. It has dark, red single flowers similar to its pollen parent, Boreas.

The rationale for making this particular cross is that it works, whereas backcrossing to Martha W. or other lactiflora cultivars does not. I have made countless intersectional back-crosses over many years of all different types (both IBC and RIBC)and have never have a single viable seed from the (i-hybrid x lactiflora) cross. Although, both of these crosses are, in my mind, RIBC's, they are very different crosses, when you look at them in terms of their ploidy levels. One is a (3x X 4x) cross, while the other is a (3x X 2x) cross. The science of breeding with triploids, such as the intersectional hybrids, is quite complicated so, I won't go into further detail here. However, the bottom line, based on the research that I have seen, appears to indicate that the (3x X 4x) cross is approx. 3-4 times more likely to produce tetraploid progeny than the (3x X 2x) cross. Since the main objective of making these back-crosses is to produce fertile Advanced Generation Intersectional Hybrids (AGIH), this seems like a good direction in which to go. It should also be noted here, that Lemon Chiffon and other similar fertile (presumed) tetraploids are in general more than 50% lactiflora.

Hi Bob
Exiting news.. look foreward to se if it flowers

This thread started back on March 10 with my post showing a picture of my reverse intersectional back-cross (RIBC) hybrid seedling, which I was expecting to bloom for the first time this spring. Well, today was the day. The first of three buds opened this afternoon. The cross which created this advanced generation intersectional hybrid was made in 2016 from the cross (i-hybrid x Lemon Chiffon). So I have been waiting a very long time for this day. This flower is shown below. Although, the foliage is very much intermediate between the two parents, the flower looks much more like the pollen parent(LC), except that the outer edges of the petals are flushed with light pink.

Congratulations Don. Thank you for sharing. That's a very exciting conclusion to a lot of hard work. The foliage looks very wide and round like LC, but has the form of intersectional.

Rob and others,

Sorry for the extremely long delay in answering your questions regarding my last post. I am pretty much off-line and disconnected during the majority of the hybridizing, growing and planting seasons, which mostly only leaves the wintertime (Jan thru April) for research, writing and correspondence. To address your questions, I used my new second generation intersectional hybrid (which I will refer to here as AGIH for Advanced Generation Intersectional Hybrid) as both a seed and pollen parent in several different types of crosses. First, I used pollen from AGLH (NB-SH-91) on two of the three flowers and pollen from Lemon Chiffon on the remaining flower. The stem pollinated with LC set a couple of soft seeds and no seeds were obtained from the other two (AGIH x AGLH) crosses. Hopefully, next year I will have a lot more flowers to work with.

A more than adequate amount of pollen was collected from these three flowers and it was used on backcrosses to it's grandmother, Martha W (16) and it's pollen parent, LC (6) for a total of 22 crosses. Only one seed was obtained from the MW crosses and so far it has not germinated. Of the six (6) crosses onto LC only two were successful and these produced 3 firm, good-looking seeds, of which two have already germinated and are now in plastic bags in winter storage until spring. So, based on this very limited amount of data, I would say that this new AGIH seedling appears to have some limited fertility, at least, on the pollen side and that its fertility as a pod parent is yet to be fully explored and clearly determined. However, based on its compatibility with LC, which is a known tetraploid, I am optimistic that it too is also a tetraploid. Next year, I hope to have more opportunity to explore its fertility as both a seed and pollen parent in a wider range of crosses. It is interesting to note here, that the two seeds that have germinated so far for me are also from the same cross (LC x AGIH) that produced seeds and seedlings for Bob Johnson (using pollen from Hans Maschke (Bartzella x LC) progeny, which he reported on earlier in this thread (see above).