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My thoughts on open pollinated/ hybrid/ heirloom plants

 
dan long
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There is a lot of talk on the net and even on these forums about keeping your plants from cross pollinating so that you can retain the desirable traits when you go on the plant the seeds next year. I respectfully disagree with this practice unless, of course, you are gardening next to someone who is growing GM crops.

We, as a human species have a very narrow understanding of what nutrients our bodies need. What we ARE pretty confident about is that variety is generally a good thing. If i plant 50 different types of lettuce this year, I have 50x more variety in my salads than Joe Smith who planted only 1 type. Next year I have an ENORMOUS variety of lettuces and therefore, a larger variety of nutrient compounds than I would get from any one type of lettuce.

Second, imagine something happens to my garden. Disease, cold, heat, drought, etc. It wipes out 80% of my crop. Well, that sure sucks THIS year, but the 20% that survived are clearly resistant to whatever calamity befell them and next year I will have resistant lettuces. With climate change on the horizon, who knows what our food will have to survive? Maybe NONE (an exaderation, i know) of the currently known lettuce types will survive whats coming, but my turbo cross-bred lettuces will.

Lettuce is just the example. This could apply to any plant.

In short, i think that open pollination and cross breeding is a GOOD thing in many situations.
 
Gilbert Fritz
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Location: Denver, CO
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Hello Dan,

You are mostly right. (Especially with lettuce, which actually crosses very little.) Your population of lettuces would gradually gain more diversity over time, becoming a locally adapted landrace.

However, for this to happen, we also have to preserve the original strains. If we mixed up all the corns on earth (corn crosses quite a lot) within a few years we would have wiped out a lot of the diversity. (Unless you maintained a HUGE population of corn each year.) If nobody kept pure strains, various genetics would be lost. In other words, to benefit from diversity, we need to preserve diversity.

Also, in some cases, the results would be inedible. If you grow zucchini, and a neighbor two houses down grows gourds, the bitter gourd genetics would soon overcome your pleasant tasting squash genetics. Bitter wild lettuce with milky sap might cross with your lettuce population and overwhelm it. Any brassica will cross with weeds ( and one another; cabbage, kale, Brussels sprouts, etc. are genetically one species.) Carrots will cross with Queen Ann's Lace, a common wild flower, and the resulting carrots would be small, white, and fibrous. Most of our crops have come a long way from their wild ancestors. While the wild plants may have important genetics to give, we will want to also keep the results of thousands of years of plant selection and breeding.

But you are right; we should each create our own land races which would be best suited to our climates, soils, and preferences. We can then select various new varieties out of the resulting genetic soup, furthering and continuing the evolution of our crop species. I think the best ones to do this with are inbreeding plants which cross a little, but not much. So every year, in addition to the parent varieties, there would be a few hybrids. If these were undesirable, it would be easy to rouge them out.

Finally, we have to be very careful to keep seed sold under a certain variety name pure, or we will cause confusion and disappointment for the buyer.
 
dan long
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That makes a lot of sense. Thank you for enlightening me.
 
Wes Hunter
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Location: Seymour, MO
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Dan, I'm not sure I follow your line of reasoning. I will keep with your lettuce example for ease.

First, most heirloom varieties (and newer open pollinated varieties) were developed from and for a certain geographical location, such that they have developed to thrive within a certain climate. Out-crossing isn't going to change this.

Second, I would contest the idea that 50 varieties of lettuce equals 50 times the nutritional variety. There is certainly a lot of overlap between lettuces; some varieties might have a bit more of this or that than others, but not drastically so. A varied diet that consists of lots of different foods (i.e. more than lettuce) of course provides nutritional variety, but different varieties within one species not so much. If you want nutritional variety from your lettuces, I would think growing lots of heirlooms is going to achieve the same goal as growing lots of hybrids.

Third, regarding your disaster scenario, having a large variety of hybrid lettuces isn't necessarily going to provide better insurance against catastrophe than having a large variety of open-pollinated lettuces. Some of the hybrids will survive, some will die; some of the OPs will survive, some will die. The benefit ascribed to genetic crosses--"hybrid vigor"--is generally only good for the first generation. That means that in order to have a 'superior' hybrid variety you must have parent open-pollinated varieties; those genetic lines must be maintained. I can't imagine that your "turbo cross-bred lettuces" would survive an event that killed all of their parent open-pollinated lettuces; after all, where did the cross-bred lettuces get their genetic ability to withstand the event from in the first place? For that matter, the reason that we have the varieties we currently have is because they have withstood "disease, cold, heat, drought, etc." Those aren't new, up-and-coming problems the gardener (and garden) must face.

You can take your hybrids and breed them back and cross them and such, and develop a new variety that is now perhaps better suited to your own microclimate, but once you've gained that stabilization all you have is a new open-pollinated variety, and we're back where we started. Cross-breeding to create new varieties is great, but that's what many heirlooms are: the result of previous cross-breeding.
 
dan long
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You reply makes a lot of sense to me as well, Wes. More, in fact, than what i wrote myself. Thank you.
 
William Whitson
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Location: Washington coast
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Gilbert Fritz wrote:
However, for this to happen, we also have to preserve the original strains. If we mixed up all the corns on earth (corn crosses quite a lot) within a few years we would have wiped out a lot of the diversity. (Unless you maintained a HUGE population of corn each year.) If nobody kept pure strains, various genetics would be lost. In other words, to benefit from diversity, we need to preserve diversity.


If everyone mixed up all the corn varieties and then selected what grew best, we would end up with more locally adapted varieties of corn than we had before. The genetics would be reallocated, but we wouldn't necessarily lose anything. The old varieties would go away, except in places where those phenotypes were particularly successful, but the new varieties would still encompass all of the diversity that existed before.

Gilbert Fritz wrote:
Also, in some cases, the results would be inedible. If you grow zucchini, and a neighbor two houses down grows gourds, the bitter gourd genetics would soon overcome your pleasant tasting squash genetics. Bitter wild lettuce with milky sap might cross with your lettuce population and overwhelm it. Any brassica will cross with weeds ( and one another; cabbage, kale, Brussels sprouts, etc. are genetically one species.) Carrots will cross with Queen Ann's Lace, a common wild flower, and the resulting carrots would be small, white, and fibrous. Most of our crops have come a long way from their wild ancestors. While the wild plants may have important genetics to give, we will want to also keep the results of thousands of years of plant selection and breeding.


This overlooks two things. First, pollination declines dramatically with distance, so if you have a stand of zucchini in your yard and a neighbor grows gourds, you'll usually get a little crossing with the gourds, but mostly just zucchini. Second, if you are going to breed plants successfully, you have to select the plants with the traits that you desire. So, when you find a zucchini with undesireable gourd characteristics, you simply pull that one and don't allow it to contribute to the next generation. In rare cases, you may actually get a useful contribution from the gourds that you would not otherwise have seen.

I grow lines of cabbage, turnips, rutabagas, mustards, broccolis, cauliflowers, etc. all in a single acre with no cross-pollination controls (and we keep bees) and find that cross pollination is not much of a problem. Sure, I get interesting crosses every year that go to the table or the compost pile, but most of my types stay true. It would be a mess if I were trying to preserve specific heirloom varieties, but I am happy to just take seed from the best of every year, even though that means that every year is a little different.
 
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