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The Hybrid Delemma

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The Hybrid Delemma

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The Hybrid Delemma

Pick up a seed catalog, any catalog that does not cater exclusively to those who prefer open-pollinated "heirloom" varieties, and flip through the pages. Seldom will you go more than a page or two before you encounter a "hybrid" variety of vegetable or flower. How can you tell? Such plant varieties will be labeled clearly as such, with the word hybrid, or the designation "F1." So if you are a gardener who has become convinced that hybrid varieties are somehow harmful, you have no excuses - these seeds are easily avoided.

But should they be? What is it about a hybrid variety that has so many gardeners looking down their noses? For that matter, what the heck is a hybrid variety, anyway?




The last question is actually the first that should be addressed. After all, how can you pass judgment on a thing when you don't understand it? (Okay, I know politicians do that all the time, but we're gardeners, remember?) At its simplest, a hybrid plant is one with two unrelated parents. Grow two summer squash plants in your garden and let the bees do that thing they do so well, and save the seeds. Plant them in the garden next summer, and the plants that come up are hybrids. (Whether or not they will be worth much depends on whether or not their parents were themselves F1 hybrids, something we will get to shortly.) Doesn't sound like much to get polarized about, does it? But this defines what a hybrid is, without saying much about how we put this bit of botanical science to use. And that, as usual, is where things get a bit more complicated, and where some people grow uncomfortable.

Hybridization is a tool essential to the science and art of plant breeding, that part of agriculture that makes possible the myriad variety of plants available for our gardens, and plays a crucial role in keeping Humanity a step or two (though sometimes it seems like less) ahead of mass starvation. In some breeding programs two plants (usually but not always of the same species) that have traits - color, flavor, disease resistance, etc. - that a plant breeder thinks would create a useful and/or profitable plant, are brought together and cross-pollinated. The seeds from these crosses are planted out and the progeny (the so-called F1 generation) are screened for the best combination of the desired traits and segregated from others of their own kind. What follows are years (sometimes many years) of careful selection and back-crossing with parental types that ultimately bring about a new plant variety. The open-pollinated varieties most of us prefer these days began their careers this way.

There are high stakes involved with some of these breeding programs. An amazingly novel color or color combination in a flower, or a more nutritious variety of corn, can literally be worth millions of dollars. To make the process more precise, plant varieties are often bred to express a limited range of traits. These varieties are pure bred lines that can be crossed to create a different variety with a highly desirable collection of characteristics. The process can be taken a step further when such pure bred lines are carefully inbred - sibling-sibling crosses, or parents with offspring (sometimes more complicated crosses between the two groups) - to create lines of plants with very specific traits. These inbred plant lines exist as vehicles, carriers of genetic material in a relatively pure form. They often bear little resemblance to the plants of the same species we desire in our gardens, and in extreme cases can be so fragile due to inbreeding that they only grow well in protected and carefully controlled conditions. All of the above are important tools of the trade for plant breeders, and two such lines can be brought together to produce something truly grand. Say you have an inbred line (or pure bred line) with extra sweet fruit that, unfortunately, succumbs quickly to powdery mildew, and you are able to cross that line with another that has so-so fruit but strongly resists the fungus. If the cross works out (there are no guarantees) you could have tasty fruit on a plant that will live long enough to bear a harvest.
Believe me when I say I'm over-simplifying for all I'm worth. They write entire textbooks and teach university level courses just on the subject of creating the pure bred and inbred lines and then using them. The goal here is to understand what the catalogs mean by hybrid variety, not to lay out the blueprint for becoming a plant breeder in your own back yard. (Which can be done, if you want to make that kind of commitment to gardening.)

Remember the catalog designation "F1?" That imaginary successful result of crossing pure bred or inbred lines - the disease-resistant variety with sweet-tasting fruit - is an "F1" plant. Together with its siblings resulting from that cross, it forms the F1 generation. This is plant breeder shorthand for the generation of plants grown from seeds of any cross of two specific parental lines.

In the case of hybrids resulting from inbred line crosses, not only are the desired traits abundantly expressed, a thing called heterosis occurs. You might have heard of the phenomenon under a less technical name: hybrid vigor. Heterosis is still not well understood, but what it means is that the F1 progeny of the cross between two inbred lines are more vigorous and productive than either parent. Sometimes a lot more vigorous! Hybrid vigor is especially useful for those trying to grow plants in marginal conditions, since the F1s frequently out-perform non-hybrid varieties in tough times. The large-scale use of such hybrids in agriculture has more often than not helped to increase crop yields enormously.

None of which sounds even remotely worrisome. Except that there's a catch (and this brings us back to question number one: are hybrids bad for gardening?) You can't save your own seeds from these F1 hybrids to grow next season. Oh, you can save them all right, but when you plant them there is no telling what you will get. F1 hybrids are a one-shot deal. The seeds that come from the fruit of plants grown from F1 seed (technically called F2 seeds, by the way) will produce plants with wildly varying characteristics. In other words, they won't breed true. Each time plants (or animals for that matter) reproduce, they shuffle their genes to create new combinations. In the wild world beyond our fields and gardens, this shuffling creates the biological diversity that gives plants and animals the flexibility they need to adapt when environmental conditions change. (It is also why so much careful breeding goes on before the hybrid variety is produced, because only in that way can we to some degree control the results of that shuffling.) There's no way of telling, from looking at the seeds in your hand, what the plants will ultimately become. Will they be like their direct parents? Or revert back to the grandparents? You might get some good stuff, and then, you might not. Usually not, in fact.

In contrast, consider open-pollinated varieties, which are often referred to as "heirloom" varieties for the simple reason that so many of them have survived only because far-sighted gardeners have kept them going. In a sense most of these plants are hybrids, since their seeds are the results of unrelated (and often random) pollination events. These varieties are not as uniform as F1 hybrid varieties (although you won't always know this when you grow them), but have enough uniformity to provide reliable performance because they have been carefully selected over many generations (of plants and - sometimes - of gardeners) for specific combinations of traits. You can save your own seeds this year and plant them the following season, and the results will be comparable to what you saw before. (And because they are not genetically uniform, sudden changes in conditions are unlikely to cause a complete crop failure.)

The F1 catch is the essence of the debate over hybrid varieties as being either "good" or "bad" for gardening and for agriculture generally. Because the vigor of F1 hybrids tends to get them established evenly and quickly in a garden or a farmer's field, they are popular with people for whom predictability means absolutely everything. This is not to say that open-pollinated varieties are generally less reliable when it comes to establishing a "stand," as the pros put it. Some compete very well in this matter. However, in situations where the environment might be marginal, or where a particular pest or disease may be prevalent, an F1 hybrid that combines so-called hybrid vigor with a specific resistance to bugs or a fungus can make all the difference between success or failure. With such a choice, and facing such a risk, which plant would you select - especially if your livelihood (in some cases your life) depended on it? The downside is that farmers and gardeners alike become locked into dependency on seed producers for new supplies of the F1 seed. A bad thing? It can be. When this reliance leads to the casting aside of traditional, locally adapted open-pollinated (heirloom) varieties, the overall gene pool of domestic plants is eroded, and that is very definitely a bad thing.

When you try to decide whether or not hybrids are bad for you as a backyard gardener, it becomes time to consider context and perspective. In large-scale agriculture the over-reliance on any single trick or technique is dangerous, a lesson certain pesticides should have long since made abundantly clear. It's the same with hybrid varieties. If you use only a few of them (or just one!) to the exclusion of all else on the grand million-acres scale of modern farming, and some pest or disease mutates in a way that turns former advantages into liabilities, you can end up in big trouble. This is what happened to corn growers in the Southern and Midwestern U.S. in the 1970s when a relatively unknown fungus spread like wildfire through genetically uniform fields of hybrid corn. The losses were enormous.

To answer such a challenge the plant breeders go to work breeding new varieties that have resistance to the new pest. But where do you turn to find the genetic material that might contain the keys to creating yet another new variety, one that resists the new plague? Older, open-pollinated varieties are the raw materials for plant breeders, but if no one grows them anymore, what is there to work with? There are other drawbacks to large-scale agriculture being dependent on hybrids, such as an increased reliance on synthetic fertilizers and chemical pesticides, but compared with the long-term cost of lost crop genetic diversity, these other concerns are rendered insignificant. After all, we can (with considerable effort) restore soil damaged by badly managed chemical input, but once we've lost the genes contained by a variety that resists a specific disease, that loss is permanent. There's an old saying: Extinction is Forever. This is not a joke.

At the other end of the scale, however, you have my back yard. The debate over whether or not to use hybrid varieties becomes very different when you switch from big-time agriculture to home gardening. Should I avoid F1 hybrid varieties because of the risk posed to large-scale agriculture by an over-reliance on such? For me, the answer to the question is a definite "No!" Hybrid varieties, when properly used, are too useful a tool to dismiss out-of-hand. As such they have often found a place in my garden, and will continue to do so. Their hardiness and vigor are often all that makes it possible to get some of the results I desire from my small desert garden, where the concept of 'marginal conditions' often needs to be revised from week to week! My best example is the "Early Girl" variety of tomato. In the fifteen years I've gardened in the desert I have yet to find a variety of tomato meant for fresh-off-the-vine eating that produces as reliably and abundantly as this classic example of a hybrid plant variety. Into this indeterminate tomato have been bred such traits as earliness (needed to insure fruit set before extreme summer temperatures kill tomato pollen) and resistance to a pernicious root disease (fusarium) that is endemic to our warm desert soils. If there is an open-pollinated variety of tomato that can match "Early Girl" in performance in my neighborhood I have yet to encounter it. (I am still open to suggestions, if anyone has one.) Until I do, I will cheerfully plant the seeds of this hybrid tomato each spring, and without a trace of guilt plant those seedlings out to my garden. I grow them because, for my backyard (and in my opinion), they are the best choice I have available to me.

Yes, this makes me dependent on the seed suppliers for as long as I stick with this tomato variety. But as long as this choice remains affordable (it is) and continues to provide the desired results, it is a dependency I can live with.

I plant hybrid tomatoes, but grow heirloom chick peas, fava beans, lettuce, and cucumbers (to list but a few). In fact, the majority of the vegetables and herbs I grow are open-pollinated. I urge and encourage fellow gardeners to grow open-pollinated varieties and practice seed-saving whenever possible, because the backyard gardener has always been (and perhaps always will be) in the vanguard of those who preserve the genetic diversity modern agriculture will need in order to survive. But I am not a purist; I am a practical gardener doing my best to make informed decisions that will lead to a successful garden. For this reason I do not buy treated seed or use synthetic pesticides. I understand that in the big bad world, hybrid plant varieties have created long-term problems for agriculture. But I also know that growing a few in my garden really does not connect with that issue. I grow the plants that work best for me, under circumstances dictated by my local climate, geography, and ecology. And by selecting the plants I grow from this perspective, I end up with a varied and diverse garden that (usually) rewards me with good harvests.

Some of the plants I grow, when you look them up in the catalogs, will bear the designation "F1".

About the Author
Thomas Watson is graduate of the University of Arizona College of Agriculture, where he earned a BS in Agriculture, majoring in plant sciences. When he is not writing he is usually working in the garden, re-landscaping his Tucson home, studying botany and plant identification, or "out there" somewhere, studying the natural history of the Sonoran Desert. This is all, of course, based on the assumption that it isn't baseball season, in which case he'll get all of the above done before the next Diamondbacks game.

About this Author

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