Does self-pollen compete with cross-pollen?

[TheWaterbug]

I'm asking because I have dragonfruit varieties that need cross-pollination, but I suppose the question is valid for other plant species as well:

If a plant cannot be pollinated by its own pollen, but its own pollen gets brushed onto its stamen stigma, will the incompatible pollen then prevent successful pollination if compatible pollen is also brushed on?

e.g. will the bad pollen be "ignored" by the flower, or will it compete with the good pollen?


edit: fixed error

[Finca La Isla]

Interesting.  I don't think that the self pollination would preclude cross pollination.  You could open the flower before the pollen is ready and remove the anthers, see if you get better set.

[ricshaw]

Many of us Dragon Fruit growers collect pollen from different varieties' flowers and mix the pollen together before we hand pollinate the flowers.

[TheWaterbug]

Many of us Dragon Fruit growers collect pollen from different varieties' flowers and mix the pollen together before we hand pollinate the flowers.

I'm starting to do this as well, but if I only have 2 varieties flowering right now, I'm wondering whether half of my pollen mix is incompatible, and whether that "crowds out" the other half.


My understanding of pollination is that the spermatozoa from the pollen grains have to grow long, narrow pollen tubes through the stigma to reach the ovules, where fertilization takes place. There are several mechanisms whereby this can be interrupted, and the specific mechanism for dragonfruit might determine what happens when there are multiple strains of pollen "competing" for a spot.

[fyliu]

https://en.wikipedia.org/wiki/Pollen_tube

The pollen makes their own tubes to get to the ovules. It's not like a protein where you can prevent another molecule from binding to a receptor by binding to it first. Which ever pollen can make the tube the fastest will get there.

I think there are enough space in the stigma for both compatible and incompatible pollen to hang on. It shouldn't take too much compatible pollen to get fruit set.