A flower which may be very fertile fails to produce seed because the style is too long for the pollen tube (down which the nucleus of the pollen must travel) and thus fertilization cannot take place. While I was in England last summer I was shown a very ingenious solution to the problem when I visited Gregory & Sons’ nursery at Nottingham.
A quote from Rose Breeding Around The World.
Has anyone had practical experience with it? How does it work?
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I cannot help you but welcome and good question!
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I have some vague recollection of people discussing cutting the style before pollination to shorten the distance the pollen tubes need to grow. But it is a very vague recollection
Perhaps someone else will remember more details about the technique
Is this the one? Long time ago.
Seem to remember one back recently - but nothing specific.
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I found and attached you two text passages of older threads Feb 05 and Sep 11, David Zlesak, regarding the cut style technique.
My rose breeding mentor, Elton Strack, tried it in the late 1980’s. I don’t think it was very successful for him. In lilies I’ve used it to generate wide intersectional crosses. Subsequently, I rescued the embryos before the endosperm failed and matured them in tissue culture. I also generated some selfs in Easter Lily this way as well.
The main purpose of cutting the style is to reduce the length the pollen tube has to go. With cut styles and lilies at least the pollen tubes don’t grow normally and tend to twist a lot, so if you have a cross where it is not necessary to use the cut style technique it is better not to do it.
For roses it might be helpful to get around self-incompatibility and may aid in some wide crosses. It seems very meticulous and one would need to be very careful to not let the cut surface dry out while the pollen is germinating and the pollen tubes are starting down the remainder of the style. With lilies there is a lot of stigmatic exudate produced, so I place some on the cut surface before pollination to aid pollen germination. With roses the quantity of exudate is much less relative to lily. Perhaps one can drop some solution like I reported for hanging drop pollen germination assays (.75% sucrose 40ppm boric acid) in a recent RHA article onto the surface to help stimulate pollen germination.
Another approach is to use heat. 100F in lilies can breakdown the self-incompatibility proteins in the style and allow for selfs as well as wider crosses. In roses in a hot greenhouse in summer I can get some selfs on some normally self-incompatible roses. Perhaps heat can aid pollent tube growth, if indeed that is the limiting factor in the particular cross, with wider crosses in roses as well.
David
Sep 11
For the cut style method, cut the styles shorter, take another bloom with sticky stigmatic exudate that you can transfer over the cut styles and then pollinate. Things are disrupted, but in some cases if that is where the barrier is occurring, it can be overcome hopefully at a good frequency allowing for some seeds. For the LA lilies, we cut the style to a quarter to half inch above the ovary in the Easter lily female parent, cut the style down the middle lenthwise, opened it putting pollen and exudate inside. We wrapped parafilm around the cut style with pollen inside to keep it moist. In a couple weeks we put the ovary in small slices in culture. The endosperm of the seeds fail (source of nutrition) due to th wide crosses and incongruity, but the embryos are generally viable. By putting the little chunks with several ovules at a time onto media, we can nourish the embryos and keep them growing instead of starving to death from lack of viable endosperm on the parent plants and get viable hybrids.
David
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Thank you for the effort you have made.
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With pleasure, you are always welcome!
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