1. not sure if tomato will cross with eggplant, but there is always a chance. I have a neighbor who planted eggplant right in with his japeno peppers and claimed the eggplant was too spicy to even eat, so who knows?

2. Yep, you can cross tomato to tomato, but you will have to do it by hand, mark flowers etc, and keep good records. Plant out enough seed and you could find what you are looking for.

3. In your trying to cross tomatoes with everything and anything, if you keep it to the solanacea family you will have better luck. That would include pepper, potato, jimson weed, tobacco, tomato, eggplant, mandrake, deadly nightshade and petunia. etc.

Here is a link that might be useful: solanaceae breeding

Yes you can cross a tomatoe with an egg plant I planted cherry tomatoes near my egg plants the results black cheery tomatoes and the taste is amazing!

As far as I've heard (other than yesilee04 above, which I'm curious to hear more about) eggplants and tomatoes are not known to cross. They are in the Solanum genus, however (so, it's perhaps possible). I wouldn't count on it, though (let alone on it crossing well or easily). You certainly shouldn't have to worry about isolating your eggplants and your tomatoes from each other. If you do happen to get such a cross, you should take a lot of pictures and post them (and definitely save seeds from it to grow again and distribute).

I'm doubtful of the mentioned cross between a pepper and an eggplant. Eggplants can be toxic if they are overripe or underripe, and the neurotoxins (which can cause your throat to burn) may have been mistaken for capsaicin. If this happens, please don't eat that eggplant. I did that once, and it made me kind of sick for about a week (though the only symptom the first day was my throat burning).

Most of the toxins in eggplants are right under the skin or so, I've read. So, peeling the eggplants is supposed to be a great precaution against ingesting too many toxins. If your eggplant is so ripe that it has changed colors, don't eat it (it's too ripe). Generally, you're supposed to pick them soon after they stop growing (or thereabouts), unless you're saving them for seeds.

As for what crosses well with tomatoes, generally the only things I know about are other tomatoes and many species of wild tomatoes (there are some wild tomatoes that don't cross easily, however). There is only one species of domestic tomato (if you don't count the inter-species crosses as other species of domestic tomatoes).

If you cross a white beefsteak with a yellow pear tomato, I'm not sure what you would get. I would guess a yellow pear, but I could be wrong. Whatever the case, if you grow out the F2 seeds (enough of them) you should get plants with different combinations of the traits, and you may end up with a white pear plant in the F2 generation.

1. Can a red beefsteak tomato cross well with an eggplant?

As far as I know....it would be a freak of nature if this happened. To my knowledge, it cannot happen "naturally".

2. Can a white beefsteak tomato and a yellow pear tomato cross to make a white pear tomato?

You can cross any tomato variety....ie, current, cherry, or slicing/paste/beefsteak etc....together. It is a lengthy process of careful selecting, hand pollination, growing out, recognizing desired traits and then saving that seed and doing grow outs for another 6 or 7 generations until the genetics stabilize....always being careful to select for the same desired traits.

3. What vegetables or fruits cross well with tomatoes?

Only other tomatoes as far as I know.

Something else to remember is that it is hard to bred for pre-desired traits. It takes a lot of knowledge of alleles, recessive and dominate genes etc... It is much easier to find a happy accident that you like and go from there.

Also, you won't see the f1 until you actually grow out the seed of the fruit.

For illustration purposes....if you cross a blue tomato with a red tomato....you are not going to see a purple fruit on that plant the same year. The fruit of a plant is the ovary of the plant (a.k.a female reproductive organ).

The fruit of a plant will become what ever the genetics of the mother plant says it will become, because it is her ovary. So, that "purple" tomato won't/can't come about until you grow out the "children".....(plant the seeds "children" you collect that year, grow them out and see the mature fruit of that f1 plant in the next year).

The only exception to this would be something like corn...because we eat the seed "children" not the ovary of a corn plant and we would usually know if a Blue Corn x-bred with a Red Corn....because the seed would/could indeed be purple.