Seedfork said:I would have thought that the process of forcing a bloom open, pollinating it before it opens naturally then sealing it up again would in itself be enough to cause a very low success rate.
It might until the experimenter becomes expert at doing so, but safe hybridizing techniques are used by plant geneticists and professional plant breeders without running into very low success rates due to the techniques used. The test for self compatibility and self-incompatibility should always have the control for the damage done by the technique by repeating the technique but instead of self-pollinating the cultivar's flowers simply cross-pollinating them.
Part A is to self-pollinate cultivar A x cultivar A using safe hybridizing techniques and record the success rate.
Part B is to cross-pollinate cultivar A x cultivar B using safe hybridizing techniques and record the success rate.
All plants of cultivar A and cultivar B must be treated in exactly the same way both before, throughout and after the test pollinations.
If the success rate is normal and much greater in Part B than it is in Part A then there is self-incompatibility.
The two rates would be compared using statistical analyses to determine if any differences seen were significant or just due to chance.
Other tests would need to be conducted to make certain cultivar A was pod-fertile and that it was pollen fertile and that cultivar B was pollen fertile. As well the tests would need to determine just how fertile A pods, A pollen and B pollen were when used in the tests.
The tests would all need to be repeated with cultivar A and cultivar C and so on until a sufficiently large number of diploid cultivars had been tested in different combinations to make a generalization reasonable.
Imagine using safe hybridizing techniques on tomato flower buds and other small flowered plant species. It can be done successfully at reasonable success rates as I can testify as I had do just that during a summer job when I was a student many years ago.
Toru Arisumi, a USDA plant geneticist did many crosses to investigate the genetics of red-flowers in daylilies. This is what he wrote in an article about his findings, "A direct and theoretically desirable method of studying segregating populations was to self the progenies obtained in Group III. These plants, however, produced little or no seed when selfed, and the few seedlings obtained from them did not survive long enough to produce flowers. I have grown a few selfed seedlings from other crosses that were as vigorous as their parents but these were exceptions rather than the typical inbred seedlings. Stout found that incompatibilities often prevent selfing and that selfed progenies are "usually so weak from loss of heterosis that they are worthless"
There are sometimes other ways to practice safe hybridizing. For example, one can hybridize in greenhouses that are kept insect-free. One can try removing petals, sepals and stamens from buds before they open naturally (removing landing places for flying insects), pollinating them and then protecting the style and stigma with straws or other devices, etc.
