By Dan Gill
LSU AgCenter Horticulturist
Home gardeners typically get along very well without delving too deeply into the science of horticulture. Genetics can be a particularly challenging area of science related to gardening.
But when gardeners have questions about hybrids, F1 hybrids and genetically modified organisms (GMOs), some knowledge of genetics is needed to understand the answers. In the area of home vegetable gardening, these terms may even be considered troubling and controversial by some gardeners. So with that in mind, let’s take a look at these terms, what they mean and how they relate to home gardening.
In botany, a hybrid is the offspring of two plants of different varieties, cultivars, species or, rarely, even genera. Plants must be fairly closely related to interbreed. Hybridization allows us to combine the desirable characteristic of two dissimilar parents in their offspring. An example would be breeding a rose with double red flowers with a rose with single white flowers. When seeds that result from the cross are planted, hopefully an offspring with double white flowers will be found.
To propagate a desirable hybrid plant, vegetative propagation using cuttings, division, grafting, layering or tissue culture will produce offspring genetically identical to the parent with all the same desirable characteristics. There are numerous examples in gardening. Most of the ornamental shrubs and herbaceous perennials we grow are vegetatively propagated hybrids.
Understanding how to create F1 hybrids and use them successfully in horticulture and agriculture is relatively new — only about 100 years old. Corn was the first plant used to successfully create F1 hybrids.
Producing F1 hybrids means first developing true breeding lines. These lines are created by inbreeding until the lines breed true. When individuals within a true breeding line are crossed with each other, the resulting offspring very closely resemble the parents.
When you cross two different true breeding lines with each other to combine the desirable characteristics of the parents, the result is F1 hybrid offspring. F1 stands for the “first filial” generation — the first generation produced when the two true breeding lines are crossed.
Perhaps an example using dogs will help explain this. Toy poodle and Pekingese are two true breeding lines of dogs. These breeds were created by inbreeding (mating sons to mothers, fathers to daughters and brothers to sisters) to fix the desired characteristics into the breed. Once done, mating a toy poodle with a toy poodle results in toy poodles, and mating a Pekingese with a Pekingese results in Pekingese. (This applies to every other dog breed.)
If, however, you cross these two true breeding lines, poodle and Pekingese, you produce an F1 generation of peekapoo puppies. The peekapoos are a blending of toy poodle and Pekingese characteristics, and peekapoos all look very similar to one another.
You would almost think it is a breed — peekapoos are very recognizable. One of the great advantages of F1 hybrid offspring is their uniformity. But if you breed a peekapoo to a peekapoo, you will not get peekapoo puppies. Some of the puppies will look mostly like poodles, some mostly like Pekingese, and some will look in between.
F1 hybrids do not breed true. You cannot save and plant the seeds of F1 hybrid plants and expect to get another uniform and outstanding generation.
Mules are also F1 hybrids — the result of breeding horses and donkeys together. Mules are sterile and cannot breed, but they are an excellent illustration of another aspect of F1 hybrids — hybrid vigor. Hybrid vigor makes mules stronger and tougher than either the horse or the donkey parent.
A large number of vegetable cultivars we grow today and many flower cultivars are F1 hybrids. They are popular for their outstanding performance in gardens, including increased vigor, more produce, improved stamina, tolerance to adverse growing conditions and excellent uniformity in characteristics like height, rate of growth, time of bloom, pest resistance, time of ripening, etc.
Genetically modified organisms
While hybrid and F1 hybrid plants originate from breeding techniques long used by humans, genetically modified organisms are a modern innovation created in the laboratory by inserting specific desirable genes into the genetic material of a plant. These desirable genes may even come from vastly different organisms that would never naturally cross with the plant.
While I’m not going to delve into the pros and cons, moral objections and controversy surrounding this new technology, one particular matter needs to be cleared up for home gardeners.
No GMO home vegetable seeds are available and never have been. Unfortunately, some seed companies are trying to take advantage of the fear and concern some gardeners have about GMO cultivars by advertising that they do not sell GMO seeds. But no seed companies sell GMO seeds to home gardeners — whether the company publicly states it or not.
I hope this information has helped you better understand hybrids and F1 hybrids, two important groups of plants for home gardeners. And when it comes to GMO seeds, you need not be concerned that you might unintentionally purchase and plant GMO seeds in your vegetable garden. You can’t.
Many bedding plants like this Magellan Coral zinnia are F1 hybrids that won’t breed true from saved seed. Photo by Rick Bogren/LSU AgCenter
No GMO home vegetable seeds, such as those for these bell peppers, are available and never have been genetically modified. Photo by Rick Bogren/LSU AgCenter