Hybrid vs. Heirloom

[Germinator]

I have a question that maybe some of your experts out there can help me with. I always thought that there was a definitive dividing line between hybrid and heirloom tomatoes. Something I read recently makes me wonder now. It refers to a book by Carol Deppe named "Breed your own Vegetable Varieties". I don't own the book (it was published in 1993 and may be out of print) but from a short clip from that book that I read, I gather that there is not really much difference.

I am experimenting with grafting this year and wondering if I should try to graft a hybrid to a rootstock? Seems like the reason you use a hybrid is for disease resistance and that is exactly why I am grafting heirloom to rootstock.

Would love to hear any opinions/facts out there. Carolyn??

[carolyn137]

Originally Posted by Germinator

I have a question that maybe some of your experts out there can help me with. I always thought that there was a definitive dividing line between hybrid and heirloom tomatoes. Something I read recently makes me wonder now. It refers to a book by Carol Deppe named "Breed your own Vegetable Varieties". I don't own the book (it was published in 1993 and may be out of print) but from a short clip from that book that I read, I gather that there is not really much difference.

I am experimenting with grafting this year and wondering if I should try to graft a hybrid to a rootstock? Seems like the reason you use a hybrid is for disease resistance and that is exactly why I am grafting heirloom to rootstock.

Would love to hear any opinions/facts out there. Carolyn??

I read that 1993 first edition, I may still have it around here.

At that time there were some varieties sold that were represented as being F1 hybrids and actually were OP's, not necessarily heirlooms, but that was then, let me do the math, 21 years ago, but as far as I know that is not being done now.

And the above is what I know you read in her book but is now outdated . Much more awareness on the part of both commercial and home gardeners and more open comments on when an F1 has been converted to an OP.

Carolyn

[Poma_adoris]

Hi Germinator! (hmm that could be a double entendre, lol)

Disease resistance is both genetic and phenotypic (culturally related), and is not necessarily equated with whether a tomato variety is an heirloom or a hybrid.

I think different experts might have different ideas about what constitutes an heirloom, but in general it would include the idea, like any other kind of heirloom, that it has been "passed down" through generations. How many generations? No exact number that I know of.

Two things you would expect of "heirloom" varieties: 1) open-pollinated and 2) true-breeding. There are many varieties of tomatoes available which are also open-pollinated and true-breeding, but they are too recent to be considered heirlooms. For example, the tomatoes being bred by Brad of Wild Boar Farms, plus a number of members here on T'ville. Sometimes people use "heirloom" in the broad sense to refer to any open-pollinated variety.

In contrast a "hybrid" variety is not necessarily true-breeding. And, the hybrids that are sold commercially as F1 hybrids are the result of controlled pollination between 2 separately maintained breeding lines that are owned by the seed company. Hence, no one else can produce the exact same hybrid. You will see other generations mentioned in the discussions of tomato breeding here - such as F5. I won't go into details on that stuff here.

Disease resistance varies quite a bit between varieties, and even from plant to plant. As you probably know, there is a whole alphabet of abbreviations for various diseases that some tomatoes have been bred to be resistant to - such as VFN - for Verticillium, Fusarium, and Nematodes (usually meaning root-knot -- these are actually animals, not a fungal or bacterial disease, but that's a technicality). Now there are varieties with resistance to more than one strain of Fusarium, so you might see VFFNT = resistant to 2 strains of Fusarium.

Hybrids are able to have those alphabetic strings attached to their names because they have been bred & tested for resistance to them. Some heirlooms do have resistance(s), but they usually have not been specifically tested-for and identified. In each case, it would be fair to suppose a variety was "selected" for resistance over the years to any diseases that were a major problem in the area where it was being grown, otherwise it wouldn't have been propagated.

Root-knot nematodes, for example, are usually a more severe problem in sandy, warm soils than clay; but they can build up in any soil if the same crop is grown repeatedly in the same plot.

Ideally, you would have some idea of the disease problems that are most likely to be prevalent in your soil type and climate, and you would choose varieties with proven resistance to those.

Grafting to a rootstock with proven resistance is a kind of "insurance" if you don't know what resistances the tomatoes you are growing have -- which would often be the case with heirlooms and many other open-pollinated varieties. Also, the rootstock varieties are supposed to better at imparting vigor, so the plant grows bigger and produces more tomatoes. I am not sure to what extent that is true beyond the effects of improving disease resistance. The roots can only grow if the top is growing to feed them - it's a cycle - so if the top is not growing vigorously neither will the roots.

The rootstock will not improve the resistance to diseases that are not residual in your soil, except to any extent that it improves vigor. So, late blight, for instance, would probably not be reduced.

Apparently, some rootstocks are better for certain tomato varieties than others, and some can actually cause the plant to be overly vigorous in vegetative growth without increasing actual tomato production. Johnny's Seeds has a good discussion of this (link below), and actually much of what they say about "generative" versus "vegetative" applies to tomato and other plants in general, not just grafted ones. But recognizing an imbalance and fixing it are different things!

http://www.johnnyseeds.com/
assets/information/tomato_grafting.pdf

Hope this helps and is not too confusing.

[Poma_adoris]

Adding a little more, about Carolyn's comment:

"Much more awareness on the part of both commercial and home gardeners and more open comments on when an F1 has been converted to an OP."

Converting an F1 to an OP is sometimes called "de-hybridizing". For example, Gary Ibsen of TomatoFest offers some tomatoes he has done this with, such as his OP version of 'Big Beef'.

This means the "de-hybridizer" has planted seeds from that F1 and made selections from them for the plants that are most like the named F1 variety in all its characteristics - color, size, flavor, productivity, and theoretically disease resistance, although I don't know in how many cases this has actually been verified. If not identical in every way, then it is not the "same" as the F1 hybrid -- it's just a close approximation.

The de-hybridizer expects that there will be a lot of variation in the seedlings (F2) from the F1 hybrid, and that it might take many generations of selecting the "true-est" seedlings before the OP version is stable (true-breeding).

From some discussions on this topic, I have the impression that some of the tomatoes sold as F1 hybrids are rather suspect as to that, and may actually be OP's, as evidenced by how true they seem to grow from their own seeds.

[Hermitian]

There are many instances of hybrids that are stable; i.e., they reproduce true from seed when pollinated by themselves. These are typically not F1's, but have been meticulously crossed, re-enforced, re-crossed, and so on. I have encountered some people on these forums who want "tomato hybrid" to mean F1 and nothing else, but alas tomato is not the only vegetable studied by biologists or for sale by seed vendors. An article with sound references discussing types of hybrids appears here: Wikipedia - hybrid.

[carolyn137]

I know the original poster, Suzanne, very well and I think she was just referring to the comments that Carol Deppe made in that first 1993 edition of her book as to the misrepresentation of some F1's actually being OP's, as I answered in my first post, and not so much about grafting.

If there were no differences at all between a known F1 and its dehybridized version it wouldn't make any difference in terms of grafting,but the fact is that no one has the money to pay for assessment of what tolerance genes might still be present in the OP version, which would be relevant.

Suzanne and I are both obsessed tennis fans and she's probably watching the Australian tennis open right now, but poor me, I have to also be concerned with my current seed offer here at Tville.

Carolyn

[Hermitian]

The word "dehybridize": how would one go about dehybridizing a hybrid species?

[travis]

To the OP:

If you are asking whether you should graft pest and disease resistant hybrid variety scion to disease and pest resistance root stock, then ...

You should pick your rootstock for grafts depending on the pests and pestilences that exist in the soil of your garden.

You should pick your hybrid scion depending on the atmospherically active pests and pestilences endemic to your garden.

[Worth1]

About all tomatoes were hybrid at one time but not all hybrids are open pollinated.
Some tomatoes just came out as black sheep for no reason other than genes.
Really dumb answer from a really dumb person, me.

Worth

[travis]

Hermitian, before anyone gets into an explanation of how to "dehybridize" a hybrid tomato, because that is what we talk about here, tomatoes, not other species, first we have to agree on the vernacular.

So, in that case you have to agree to accept our common vernacular here at Tomatoville, e.g., "hybrid tomato variety" to us means an F1 hybrid cultivar the 100% heterozygous genetics of which is comprised of two pure breeding lines ... period. And "dehybridizing" means to us a repetitive process of growing out blocks of filial generations from seeds taken out of an F1 hybrid tomato, sequentially selecting the recombinations that exhibit the traits we wish to stabilize, and eventually arriving at a stable, open pollinated line.

[joseph]

My definition of dehybridizing doesn't require that the end result is a stable (highly inbred) homozygous cultivar. I am quite content with doing dehybridizing that results in many cousin lines being grown as a family group rather than as pure mono-cultured varieties.

[zipcode]

Most modern hybrids already have a lot of the disease resistance that rootstocks have.
From what I know commercial growers (with lots of money) usually use grafting of hybrids to get that perfect balance of vegetative/generative for their conditions that will get the most yield. This could be worth it if you use expensive seeds (some will cost 1 euro per seed even in bulk) and are growing in costly conditions (like in winter), but probably not worth it for the casual commercial grower.

[Redbaron]

Originally Posted by Germinator

I have a question that maybe some of your experts out there can help me with. I always thought that there was a definitive dividing line between hybrid and heirloom tomatoes. Something I read recently makes me wonder now. It refers to a book by Carol Deppe named "Breed your own Vegetable Varieties". I don't own the book (it was published in 1993 and may be out of print) but from a short clip from that book that I read, I gather that there is not really much difference.

I am experimenting with grafting this year and wondering if I should try to graft a hybrid to a rootstock? Seems like the reason you use a hybrid is for disease resistance and that is exactly why I am grafting heirloom to rootstock.

Would love to hear any opinions/facts out there. Carolyn??

Let me explain something to you Germinator. Hybrids are a good thing. The bad reputation hybrids have now is the direct result of commercial breeders developing hybrids for commercial use with qualities that have nothing to do with taste and nutrition, and instead have everything to do with shelf life, mechanized harvest etc.... The result of course is the tasteless red round pieces of cardboard they call "tomatoes" (I use the term loosely) found at the grocery.

If you need proof that this is not necessarily the only way to make a hybrid, grow a sungold F1. That's a hybrid and a very good one.

So if you have found a hybrid you like, and there are a few good ones out there, by all means, you certainly can graft it.

I had a talk with Tom Wagner on the phone this summer, and we discussed this very subject. There is a place for heirlooms, and maintaining that genetic base is in fact VERY important. In fact that's why people like Carolyn and seed savers are so important. But he wished there was a term "hybrid heirloom" or some such, to alert customers that yes indeed it is possible to make a hybrid that retains the taste and nutrition found in many heirlooms, but also containing disease resistance, productivity, and vigor found in commercial hybrids.

[Sun City Linda]

Interesting point of view Red Baron. I agree. As a Sungold lover, I think folks who turn up their nose at all hybrids are just heirloom snobs Brandyboy is another that seems to be widely appreciated, as is Fourth of July.

[Hermitian]

I think that when a breeding program is undertaken to move the desired characteristics in an F1 to something with more stable offspring, that there are many good choices of words: "hardening", "stabilizing" to name a few. From my viewpoint, it seems that the choice of the word "dehybridize" is to reinforce the false concept that the only "real" type of hybrids are F1. I believe it is a disservice to confuse gardeners with terminology that contradicts what they know or will learn about other types of plants they grow. I also believe that at one point some seed sellers thought there was a marketing advantage to vilifying F1 hybrids. This has fizzled -- I believe in a large part because of Abe's old adage: you can't fool all the people all the time.