Plant breeding question, how many fathers to make seeds

[reed]

I have a question I bet someone here knows the answer to. In theory every kernel on an ear corn could have a different father. Is that also true, again in theory and ignoring the concept of in or outbreeding, for every seed in a tomato, apple or pumpkin, every pea in a pod?  Or can a flower or fruit develop multiple seeds from just one pollen.

 

[philagardener]

One pollen in, one seed out. That's a pretty good rule.

The actual mechanics of fertilization in flowering plants are complicated (two fusion events generate separately the 2n zygote, or new plant, and the 3n triploid endosperm, a nutritive tissue that is most prominent in maize/corn kernels - but the genetic information in the single offspring originally came from one pollen grain and one ovule.)

However, all pollen grains and ovules are not equal. Some combinations may grow better and out-compete others. Pollen can also clump in some species reducing the number of male parents contributing to seed set, and in a landrace corn field the pollen diversity is not going to be the same everywhere ( Joseph Lofthouse has posted some nice graphs of how pollen counts drop off with distance from the plant shedding that pollen). And some flowers, like those peas, self-fertilize before the flower is completely open (hence the need to tear into the flower early to remove the anthers if one is doing a cross), so those are some other things to keep in mind. 

[blueadzuki]

there is also the fact that some plants (most notably some citruses) can make parthenocarpic seed (seed that arises totally from maternal tissue, and is a genetic clone of the mother) In some plants this seed tend to out grow and shove out sexually created seed. In some plants, like mangosteens, it ALWAYS does (every mangosteen tree on earth is basically a clone of every other one.)

[Carol Deppe]

Yes. Every kernel on a corn plant can have a different father. In practice, though, even in a nice big corn patch many kernels on an ear will have the same father because a certain nearby plant let off a puff of pollen and the wind current blew it just right to reach your ear. In fact, if you have an obvious off-type nearby, such as a plant with black kernels in a white corn patch, you might have all the black kernels on the ear in a little patch on one side representing that puff of wind, and not other black kernels.

Squash in a patch with many different varieties often have many fathers represented in the seed of each fruit. I think it's because the pollen is released gradually over an hour or so, and the bees come back and make multiple visits. So one flower might get pollinated and repollinated by a dozen bees, each of which had a different flight path visiting different flowers just before. Each bee transfers pollen mostly from the last flower or two it visited. But there are lots of different bee visits.