(Part 3 in a series in honor of the Durham County Seed Library)
Yesterday, we looked at the differences between open-pollinated plants and heirloom varieties. Today, we’ll explore the basics of their agricultural counterparts, the hybrid varieties.
What is a hybrid?
Hybrids are created when individuals of two different genera, species, or varieties mate. Hybrids occur in nature: Leyland cypress (Cupressus × leylandii), peppermint (Mentha × piperita), and wheat are well known naturally occurring hybrids. Next time you shop for plants at the garden center or nursery, if you see a multiplication sign (×) in the plant’s name, you’ll know the plant is a hybrid.
In agriculture, hybrids are often created by controlled pollination, a process in which the pollen of one parent is applied to the stigma of the other parent, and the flowers of the “mother” plant (the pollen recipient) are isolated (for example, securely enclosed in paper or fabric) to prevent further pollination.
F1 hybrids
F1 usually refers to the first generation produced from a specific cross of two distinct, uniform varieties (two “pure lines”). If seeds are saved from the fruits of these F1 hybrid plants, they will not be “true to type;” that is, they won’t reliably resemble the parent plant. To get a similar plant to the one that produced those fruits, a gardener would have to cross the original parents again. When it comes to vegetables and flowers, F1 hybrids are typically vigorous plants and good producers, but new seeds must be purchased year after year.
What would happen if I planted those seeds from the F1 fruit?
Unless the hybrid is sterile, plants will grow from those seeds from F1 fruits. These F2 plants (second generation) won’t look like their parent, though, and they may not look much like each other. But if you have an appetite for a long-term project (say, close to a decade), you might be able to select for good traits, save those seeds and grow out successive generations, and over time bring that variety to stability. Then you’ll have created your own open-pollinated variety, and you can name it whatever you like.
There’s so much talk about growing open-pollinated plants. Are hybrids bad?
No, hybrids aren’t bad. They fulfill an important role in agriculture, whether it’s for the backyard gardener or the large-scale industrial farmer.
Truckload of corn, Wikipedia photo released to public domain.
The problem in modern agriculture, for which hybrids receive the lion’s share of the blame, is the widespread loss of genetic diversity. We all remember from biology class that variety in a species’ gene pool enhances that population’s ability to adapt to changing conditions and survive over the long term. When farmers plant F1s heavily or exclusively, their fields are filled with identical genetic copies of one another. There is no evolution; favorable traits are not selected and propagated. And when an open-pollinated variety is not planted, it does not have the opportunity to grow and adapt to changing conditions, and over time the variety deteriorates.
Meanwhile, insects and diseases are evolving, changing, and adapting. Restricting genetic diversity in the plants we grow means that over time we’re effectively building better bugs and blights.
The long-term prospects of planting monocultures of F1 varieties include massive crop failures and famines, and/or the heavy use of pesticides and herbicides and whatever residual impacts on human health those products may have.
So hybrids themselves aren’t bad. Exclusive planting of hybrids, however, is very short-sighted.
Now I feel guilty for liking my ‘Silver Queen’ corn, ‘Packman’ broccoli, and ‘Big Beef’ tomatoes. Will I be a bad citizen if I grow them this year?
No, but try growing some open-pollinated varieties as well. You’ll need to maintain isolation distances for some crops, but that’s a matter I’ll write about later this week.
