Judging from the content in some of the threads on this forum my question may seem very basic, but I would appreciate any help you can give me. Most of the articles I’ve read on pollenation recommend that if you cross a tetraploid with a diploid, use the tetraploid as the pollen parent. Some say to make the cross both ways. History seems to point to using diploids over tetraploids. (The European roses x The China’s) I want to use my China’s as pollen parents over Autumn Damask, and Belle de Crecy. Would this even work? Mabey there are some threads already posted that can help me, but I don’t know the right genetic terms to search them out. Any help would be much appreciated.
I haven’t used diploid pollen on Belle de Crecy, but I’ve used two tetraploids (Red Flower Carpet & Kaleidoscope) and achieved decent germations. I get about six large seeds per hip. The seedlings were either completely healthy over two years, or all the leaves were immediately disease prone. After two years none have bloomed. I’ve never seen any op hips on my Belle, so many people believe it only sets empty hips. Not so. I suggest that you wait until the flower is completely open & the center is sticky before applying pollen for optimum seed set. There’s not much danger from self pollination as there are few anthers & they’re largely hidden by the petals. I have a couple of other rather typical gallicas whose names are lost, but with those I’ve only gotten about two seeds per hip & negligable germinations.
I have had op hips on Hippolyte, just next to Belle. One seedling bloomed at about 6 weeks, but it was single. This is quite typical for modern recurrent roses. Most of the roses in the vicinity of both gallicas are diploids, & this seedling had long leaves similar in shape to Lavender Dream (a “hybrid” musk by ancestry), but with the thick gallica texture.
An easier gallica to work with is Tuscany which produces hips easily & whose seeds germinate very well.
As for diploid on tetraploids, I’ve used pollen from Swany (a parent of Bonica I believe) on a tetraploid mini & got a plant that sets op seeds, but no germinations as yet.
Why not give the diploid pollen a chance & then post your results. Good Luck.
As far as my knowledge of genetics goes, I can’t think of any logical reason why diploid x tetraploid would be a better bet than tetraploid x diploid. I suppose it is possible that given diploid cells are slightly larger than haploid (generally) that the diploid pollen (from a tetraploid plant) would have more umph, so to speak, to actually grow the pollen tube and achieve fertilization, but both would almost certainly work, assuming both parents are fertile. If you can, try it both ways – some roses (regardless of ploidy) make better pollen then seed parents, or vice versa. The only way to really find out how good of a parent a rose is is to try it (or talk to people who have tried it) so experiementation is probably the best way to go.
There are theoretical reasons for thinking that diploid X tetraploid crosses are more likely to be successful than tetraploid X diploid crosses, but I’ve had some nice seedlings from tetraploid X diploid crosses. For example, this one from the cross Fragrant Cloud X Mons. Tillier. Never let theory get in the way of trying whatever you want to try!
Thanks to each of you for your help.
I seconds Jim Turner’s remarks. I use Diploid pollen on many tetraploids with great success. Case in point is the Tea, ‘Mons. Tillier’, which in my experience, is HIGHLY fertile as a pollen parent. I have hundreds of various seedlings from last year using it as a pollen parent.
Also in agreement with Jim, don’t let the theory and technical details become roadblacks to your ideas. ALWAYS ideas first! The only judgement to make should be: “Did you get results?”
PS to Jim: does that seedling have good fragrance?
Yes, Paul, that seedling does have good fragrance. I made that cross because, to my nose, Mons. Tillier and Fragrant Cloud have the same kind of fragrance. Not the same strength, of course; FC’s is much stronger. It seemed to me that you’d be more likely to get fragrant seedlings if you cross roses that have the same kind of fragrance with each other. For example, a cross between two fruit-scented roses would be more likely to produce fragrant seedlings than a cross between a tea-scented rose and a myrrh-scented rose. It is just a theory, but I’ve had good results letting my nose pick the crosses.
I first did this cross in 2000, got two hips for two pollinations, and six seedlings from nineteen seeds. Three of the seedlings were good enough that I still have them. I’ve tried the cross in subsequent years, but never got a hip to set. FC can be so fickle.