If I save seeds from a tomato...

[Tomatovator]

and there has been cross-pollination from a different variety will all the seeds from that tomato be crossed or will some be true to the variety I'm saving?

[Suze]

There can be both self-pollinated ovules and x-pollinated ovules (pollinated ovules = seed) in the same fruit. An ovary has many ovules.

[Ruth_10]

Suze, can you put some ballpark numbers on how often a fruit might have both? I.e., is this common or rare?

[carolyn137]

Originally Posted by Ruth_10

Suze, can you put some ballpark numbers on how often a fruit might have both? I.e., is this common or rare?

For starters I'm not Suze, so I hope you don't mind my initially answering and I'm sure if Suze has a different outlook she will so post.

Ruth, there is absolutely no way to speculate as to how many tomatoes might have been X pollinated or indeed the number of seeds within those tomatoes that are X pollinated.

Let's say we have a tomato ovary that has 200 ovules in it. And lets say that 199 of those are fertilized by self pollenization leaving just one ovule to be potentially X pollinated.

That's at the low extreme.

But it could also happen that of those 200 ovules, 100 are fertilized by self pollenization and 100 are X pollinated.

I've saved seeds from some varieties where I never even knew they were X pollinated , b'c the level was so low, until many many folks had grown out some of those seeds.

Let's say I process 10 fruits for seed and each fruit has 200 ovules in it. So the theoretical potential is 10 X 200 or 2000 seeds. Now lets say that 1-2 ovules in ONE fruit were Cross pollinated, and that means that theoretically about 1998-99 of those 2000 seeds are pure and 1-2 aren't.

It would take a long time of sending out those seeds to others before anyone would pick up on those 2 X pollinated seeds.

Say you have a variety that has pollen that clumps easily following high humidity or rain, and so self pollenization doesn't go the way it should, and so many ovules remain unfertilized. And lets say that nearby there's a variety that doesn't have pollen that clumps easily and so insect pollinators transfer the pollen and you end up with almost ALL X pollinated seeds.

Let's say that variety X does not normally have an exherted stigma, but it's known that weather can cause stigma's to exhert. In that case, again, insect pollinators could X pollinate that exherted stigma and it's possible that almost ALL the seeds in that fruit would be X pollinated.

My comments are obviously directed at situations where no attempt has been made to prevent X pollination.

So it's a complicated situation, as you can see, and it is impossible to predict.

But I would say under most circumstances it would be rare to have both kinds of seeds in one fruit, since self pollenization is usually quite effective.

However NCP ( natural X pollination) data has shown that the figures can range for 0 up to maybe 40% X pollination.

But that's referring to the percentage of VARIETIES having that level of X pollination.

So with 95% self pollenization it means that statistically 95 varieties out of 100 will have pure seed.

Does that help, or hinder?

[Ruth_10]

Yes, that helps. Sounds like it's likely to be not that common but something to keep in mind as a possibility, nevertheless.

I hadn't known that a single fruit could, potentially, contain both pure and crossed seeds. But thinking on the level of large numbers of ovules and opportunities for fertilization, I can see how it could happen.

Learn something new every day.

[Tomatovator]

So...if I'm saving seed from a PL variety and the seed grows PL plants there is a good chance it did not cross??? If I'm saving seed from a RL variety it would be harder to tell if it crossed?? I would have to wait to see the fruit to know??

[feldon30]

Correctamundo...