This is so interesting, thank you so much for sharing!
Great to have information on all these varieties.
It’s interesting to note the 16 cases where ploidy had been determined previously by microscopy, and that in 6/16 of them, the ploidy is now disputed with the flow cytometry method. 6/16 is quite a high proportion.
What is your take on that, @henry_kuska ? Is the cytometry result the “definitive” one?
I am just a layperson, so of course most of this stuff is way out of my league, but it did sound like an interesting prospect to one day be able to learn to measure guard cells under a microscope to find out about ploidy. However this paper seems to suggest the microscopy may not be all that reliable. Am I understanding this correctly?
The following was stated: “It’s interesting to note the 16 cases where ploidy had been determined previously by microscopy, and that in 6/16 of them, the ploidy is now disputed with the flow cytometry method. 6/16 is quite a high proportion.
What is your take on that, @henry_kuska ? Is the cytometry result the “definitive” one?”
H. Kuska comment: I did not interpret this paper to indicate that microscope results were not definitive. The present authors used the microscope method to confirm their cytometry results for their sample.
I did extensive microscope - pollen work and found some/many ? examples of samples with more than one size pollen. example - Rugelda X R15 is blooming, Pollen available
Is the pollen size dependent on external conditions such as temperature, sunlight, soil conditions, first hips of the season, later hips, etc.?
effect of soil nitrogen on pollen production - Google Scholar
Thank you @henry_kuska !
Heh, I guess I didn’t understand at all… 
Sorry and thanks for your patient reply.
Thanks for posting this paper, Dr. Kuska, and thanks to our friends at TAMU for publishing this valuable breeding information.
This was a surprise:
“We found that…Knock Out…and…were tetraploid”
I never got anything from Knockout either as female or male and mine never set seed so I assumed that it was triploid.
At least one potentially significant difference between the studies used to determine ploidy is the source of the material: David examined root tips, while the present study performed flow cytometry using emerging flower bud tissue or expanding leaf tissue. There can be differences between the ploidy of roots and upper plant parts because they originate from different layers of tissue; the ploidy of those layers (and the parts derived from them) is not identical in the case of a periclinal ploidy chimera. With such a chimera, if the different tissue layers happen to be variously tetraploid or triploid, it would be possible to end up with both tetraploid and triploid “versions” of the same cultivar over time, if new plants are generated from occasional shoots that originate solely from one or the other type of tissue layer.
Stefan
Thank you for the good and clear explanation of the two methods and how the results are obtained. In this way, the deviating results can be put into perspective.
From which layer do the gametes originate?
Gametes are generally understood to originate from the L2 tissue layer (with roots originating from the L3 layer, and epidermis from the L1 layer).
This is Dave Zlesak’s article: http://globalsciencebooks.info/Online/GSBOnline/images/0906/FOB_3(SI1)/FOB_3(SI1)53-70o.pdf