seed_packet_juliet.jpgA friend asked me a question last summer that kind of blew my mind. “If we can’t expect seeds from hybrid tomatoes to ‘come true,’ then where do they get hybrid seeds from year after year?”

Now, I definitely knew (or thought I did) what a hybrid was, and I had a canned answer for anyone who asked how hybrid varieties were made (well, breeders cross two varieties to come up with a new one). But I realized I hadn’t really ever understood the nitty gritty of hybrid seed production. I intended to hunker down and do some research, but it kept falling way down on the to do list until I started perusing this year’s seed catalogs, considering the varieties I wanted to try. When I order Sungold seeds each year, the seed company doesn’t have to continually grow the parent plants and cross them to get new seeds, right? That would be terribly labor intensive and it seems the seeds would be ridiculously expensive! Well, as it turns out, that is exactly what they do. If you’re curious to learn more, read on!

First off, let’s get a little terminology straight (if you know all of this, feel free to skip to the next paragraph). I want to quell the notion that hybrid varieties of vegetables are genetically modified (GMO). Genetic modification is a completely different (and much newer) process that involves manipulating a plant’s DNA. It’s quite complicated and I won’t go any further with it here. Open pollinated (OP) varieties produce true seeds (meaning collected seed will produce the same plant) from year to year. However, many open pollinated varieties are the result of natural hybridization that has occurred over the years. And even some varieties that were originally created through manual hybridization means have stabilized to become open pollinated types (Rutgers tomatoes are one example). Heirloom varieties have no official definition, and most are just open pollinated varieties that have been around a long time, often passed down because they had qualities gardeners liked (and they usually have very charming names). And finally, hybrid varieties are created by crossing two “true line” parent varieties, and their seeds will not produce the same plant. They usually have qualities that exceed those of their parents.

Here is a SIMPLIFIED version of the process using tomatoes as an example:
Two parent tomato varieties are identified that have desirable characteristics, such as high yield, resistance to particular diseases, great taste, etc. These varieties are well established and reliably reproduce true from their own seeds; they are “true line” varieties.

Since tomatoes flowers are complete, having both both male and female parts, and usually don’t get pollinated with the pollen of another tomato plant, the breeder has a couple of challenges to keep the plants from self-fertilizing. First, the breeder must decide which variety will have its male reproductive parts removed. This variety will then effectively become the “female” parent, the one which will bear the fruit with the hybrid seeds. Removing the male flower parts must be done manually and is quite a tedious task.

Next, pollen needs to be transferred from the variety with non-modified flowers (the “male” parent) to the modified flowers on the “female” parent. This also has to be done manually.

There are other tasks as well, including removing any fruit that resulted from self-fertilization that occurred before the flowers were modified.

Then, when the desired fruit are ready, they must be harvested and the seeds collected – another process with several steps. If this is an established hybrid already for sale, the seeds are packaged and sold as an F1 hybrid (meaning first generation). If this is still part of a test for a new hybrid, the seeds are planted the next season and tested to see if the desired traits made it into the hybrid variety.

And this process is done year after year. Amazing, isn’t it? Not surprisingly, given the immense amount of labor involved, nearly all of our hybrid seeds are being produced in China and India. Some smaller scale production is done in Mexico and Chile.

When a breeder creates a hybrid variety, they own the rights to it, and information about the variety becomes their intellectual property. Hence, we don’t know which parent varieties were used to create many of the hybrid varieties that are available. However, people have taken popular hybrid varieties, such as Sungold (F1) and tried to create their own open pollinated versions. This would take several years and several generations of plants (F2, F3, F4, etc). Basically, they collect seed from the plant and then plant them the next year. Then they select the plants that are best or came nearest to “true” and collect their seeds. Then repeat again next year, and the next, etc, until all seeds reliably produce a consistent variety. This is important to know because if you truly are after the original Sungold F1 plant, you need to be sure you buy seeds that are labeled Sungold F1. (Some of the developed OP varieties still have “Sungold” in their name – Sungold Select, Big Sungold, etc.)

Finally, if you are a risk taker and adventurous gardener at heart, and, most importantly, you have the space to spare, you can certainly try planting collected seed from your hybrid tomatoes (and F2 generation). If you do a little research ahead of time, you will find fellow gardeners who suggest hybrid varieties that are more likely to produce F2 plants and fruit that are close to “true” to the parent (F1) plant. Why some are more like to do this gets more deeply into the lineage of the parent plants of the F1 hybrid.

 

Contributed by Carey Harrington, Colorado Native Plant Master and Certified Colorado Gardener

References:
“Vegetable Hybrid Seed Production,” Seeds: Trade, Production and Technology, by David Tay
(http://www.seedconsortium.org/PUC/pdf%20files/23-Vegetable%20Hybrid%20Seed%20Production.pdf)

“Hybrid Varieties and Saving Seed,” Texas AgriLife Extension Service
http://aggie-horticulture.tamu.edu/archives/parsons/vegetables/seed.html

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