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newbie question

Posted by lalameija (My Page) on
Sat, Nov 17, 07 at 13:11

Hello All! I have perhaps what might be to some a silly question. I am not a seeds saver but would like to be. I understand how hybrids work. Cross one plant with another and you get something else. What I don't understand is plants that "come true from seed", because I often see these same plants crossed with something else to get a hybrid. I am thinking specifically of species fuchsias, but I see this all the time with other plants. How can a plant come true from seed, yet have the ability to be crossed with something else. I have several spcies plants planted in close proximity to each other, but would like to save the seeds. ANY info to help be better understand is appreciated. THanks!


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RE: newbie question

There are entire books written on the subject of why and how plants come true from seed as opposed to hybrids and I will try to squeeze it down into something simpler, though maybe not completely accurate, but hopefully you will get the jist of it.

A cultivar is a specific cultivated variety of a species. For example, "New England Pie" is a cultivar of Pumpkin (Cucurbita pepo).

A species is a specific form of a genus. For example, Pumpkin (pepo) is a specific species of squash (Cucurbita).

There are many types of hybrids, but I will try to explain the 2 most common types.

One type of hybrid is when 2 different species in the same genus sexually reproduce and create an offspring with one set of chromosomes from one species and one set of chromosomes from the other. Because of the mix of chromosomes, the offspring is often sterile and cannot reproduce. Think of a mule created from combining a horse and a donkey. The mule has characteristics of both parents, but is sterile. Thus it is with most plants. To create a flowering plant that doesn't fruit so that it will have more energy to make more blooms, this type of hybrid is wanted. In the very small chance that this type of hybrid actually does create viable seed, the seed will usually revert to its original types. Some seeds will grow to be Species A while others will be Species B.

Most flowering plants have 2 sets of chromosomes. One set from the mother, and one from the father. In nature, for the survival of the species, it is generally considered good to have different individual plants each with its own specific combination of genes. In essence, each individual plant is a hybrid in the same species.

Lets say we find a very good tasting wild pumpkin. Because it is wild, its genes will be a mix of each parent. Lets say it has 100 seeds and we plant the seeds. We plant only seeds from this pumpkin. We find that 2 of those plants produced pumpkins similiar to the original. We save the seeds from those pumpkins and grow more plants the next year, 25% which are similiar to the original, rogueing out the off-types. We do this year after year until 100% of the offspring are identical. This is now an open-pollinated cultivar and will grow true from seed. Each set of chromsomes should now be identical.

Lets say we were to take pollen from Pumpkin Cultivar A and pollinate a female bloom of Pumpkin Cultivar B. Both cultivars are open-pollinated and each has 2 identical sets of chromosomes. Each seed created in the fruit will have one set of chromosomes from the mother and one from the father. Lets say that Pumpkin A is big but is susseptible to Powdery Mildew. Pumkpin B is resistant to Powdery Mildew but is a very small pumpkin. The hybrid seed should produce pumpkins that are medium in size (somewhere between the two parents) and be resistant to powdery mildew (on one set of chromosomes it has the gene for resistance). If you save the seeds and plant them, you may end up with one or two plants similiar to the hybrid parent. Keep selecting offspring like the original and eventually, you may get an open-pollinated strain of the same hybrid.

You may have noticed that my hybridizing experience is with pumpkins instead of fuchsias, but hopefully this helps somewhat. The concepts should be fairly similiar.

Good luck.


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RE: newbie question

lalameija,

The book, Breeding New Plants and Flowers, has a section on breeding Fuchsias. It says that breeding Fuchsias is easy, and Charles Welch, the author, explains the techniques and tricks for breeding them and growing the hybrid seedlings. They show the anatomy of the flower, how to make the cross, how to germinate, and how to grow the seedlings. The book has a lot of good color pictures.

They say that if the seed is sown as soon as it is ripe, better germination results. They come up in three to four weeks and at the second leaf stage they should be potted singly in starter pots. At the fourth pair of leaves, you should take out the tip of the seedling to make the plant bush out from the three remaining leaf pairs, yielding a bush with six stems. After two pairs of leaves have grown on each of those six stems, you should nip out the tips again, which gives you a bush with 24 stems.

Interestingly, Charles Welch notes that most fuchsia breeders want to see their flowers as quickly as possible and the best way to do that is to save that first tip that you pinched from the four-leaf-pair seedling and root it as a cutting, let it grow without pinching and it will bloom long before your pinched and re-pinched plants.

If that flower looks desirable, you can take many cuttings from the bushy plant and use them as the basis for further breeding. You could back-cross them to the best of the parents, or cross them with others of your fuchsia hybrids.

I prefer to breed zinnias, because they have a much wider color range than fuchsias and they come up from seed in three or four days rather than the three or four weeks that fuchsias require. The pinching and cuttings techniques can also be used for zinnias. I have cuttings from my selected "breeder" zinnias growing inside under fluorescent lights right now. It is, in effect, already Winter here in Maine. My zinnia cuttings represent continuations of both the first and second generations of zinnias that I hybridized last year and grew and re-hybridized this year. The number of crosses you can make with zinnias is huge, because they come in such a wide variety of colors, sizes, flower forms, and plant habits. You can read more about that in the It can be fun to breed your own zinnias message thread in the Annuals forum.

MM


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RE: newbie question

Thanks so much for your replies. They did indeed answer my question!!:)


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RE: newbie question

Ok, I did get alot of information from the above posts, but the more I think about it, the more questions I have.
nwl-me, If a open pollinated cultivar is created having two sets of identical chomasomes as you stated in the first example, how in the second example, could they be crossed? Say a bee loaded with pollem from pumpkin A went to pollinate pumpkin B wouldn't that be an example of open pollinization? Shouldn't the female blossom produce fruit like itself if it is a stable open pollinated variety? I don't know if I am phrasing my question correctly. I have a hard time verbalizing.


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RE: newbie question

Although I am rather new to the forums, I will try to answer your question to the best of my ability from my own studies in genetics.

Pumpkin Cultivar A would theoretically have 2 identical sets of chromosomes. You would not want to grow it in close proximity to Pumpkin Cultivar B because a foraging bee may decide to visit both, and thereby crossing the two cultivars. To have an open-pollinated variety remain "pure", you want to separate it as much as possible from similar compatible crops.

Now, if the blossom of Pumpkin Cultivar A accidentally does receive pollen from Pumpkin Cultivar B by means of a bee or other insect, the fruit set would indeed be that of Pumpkin Cultivar A. It would taste the same, look the same, etc. The only difference now is that the seeds inside now contain the genetic material from both A and B cultivars, and planting these seeds will give you your F1 hybrid.

By keeping the pumpkins separated, you can reasonably assure that crossing will not occur. At least until you decide to crossbreed the two intentionally to get your F1 seeds. Just keep in mind that when you preform the cross, the resulting pumpkin itself is not the hybrid, but contains the hybrid seed.

Hopefully this came out the way I wanted it to, and was easy to follow. :) Hope I helped!


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RE: newbie question

Thanks everyone! BUt UUGGHH! I think I just have a hard time mentally sorting things out! Will check out some books, but great expalanations, folks! THANK YOU!


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