 Backyard Farming in the River Valley Podcast
July 15, 2009
Hybrid, Heirloom, and Open-Pollinated Crops (4:15 minutes)
Audio/Video Script:
Dustin Blakey, County Extension Agent - Agriculture
Jesse Bocksnick, County Extension Agent - 4-H
[Title slide - River Valley Gardening, Hybrid, Heirloom, and Open-Pollinated
Crops, Dustin Blakey County Extension Agent, University of Arkansas Division of
Agriculture]
[Dustin Blakey standing in a tomato garden] Have you ever wondered about the
difference between hybrid and open-pollinated varieties of vegetables and fruit?
Hi, this is Dustin Blakey with the County Extension Office. We're here at the
Learning Fields today and we're going to talk a bit about the differences
between hybrid tomatoes and old-fashioned or heirloom tomatoes that are
open-pollinated.
[Picture of a sliced tomato] First let's talk about what makes hybrid plants
different from open-pollinated cultivars.
[Picture of a wildflower field] There's nothing magical about hybrids.
Hybridization happens all the time in nature, [Picture of a man looking at a
plant] but when we talk about cultivated plants, we are referring to man-made
crosses of plants.
[Picture of Gregor Mendel] Before Austrian monk Gregor Mendel worked out the
rules of inheritance, gardeners would just save seeds from plants with desirable
characteristics. [Picture of someone holding seeds in their hand] The seeds from
bad plants were either deliberately not kept, or were not as abundant at
harvest. [Picture of people picking vegetables in a field] Over time this
developed into open-pollinated varieties. [Picture of a closeup of a corn cob
with multiple colored kernels] Each locality would then have their own favored
cultivars. This is how many of our heirloom vegetables came to be.
[Dustin Blakey standing in a tomato garden] One of the obvious differences
between hybrids and heirloom varieties is that hybrids generally are going to
have a much higher yield. They've got a better genetic background. It's more
diverse so it's going to be more optimal in more conditions.
[Picture of a flower with a bee pollinating] Heirloom vegetables are all
open-pollinated. This is because open-pollinated cultivars will self-pollinate
and yield plants that very closely resemble their parents.
[Picture showing corn pants that are inbred and ones that are hybrid] The
so-called F1 hybrids are formed when 2 strongly inbred open-pollinated cultivars
are crossed. These parents are usually unproductive on their own as they may
have been strongly chosen for a few traits at the expense of all others. When
crossed with a complementary variety that is also inbred, the result is a
vigorous uniform crop with the desirable traits of both parents.
This is what is commonly called "hybrid vigor."
Here's how it works. [Diagram showing hybrid uniformity. True Breeding
Parents with gene A are bred with gene a. Their offspring equals all same – Aa
Aa genes] A breeder has lines that are highly inbred. In the case of peas like
Mendel used flower color works well as an example. Here we cross a true breeding
pink flower, which we denote with capital As with a true breeding white flower
which has little As. The capital just means that pink is dominant over red in
this case, but it doesn't really matter. The principle is the same, but with pea
flowers you can see visually how the genes interact.
When these 2 lines are crossed, their offspring will all be pink. Each and
every plant will have 1 pink gene and 1 white gene. This is the basis of the
uniformity we see with hybrid crops.
So what happens if you save these seeds?
[Diagram showing Why you can't save hybrid seeds. Hybrid Parents with gene A
are bred with gene a. Their offspring equals 3:1 ratio – AA Aa Aa and aa genes]
When hybrid plants are allowed to self-pollinate, their parents' genes all
separate back out. With our peas, that means that you will see 75% pink flowers
and 25% white flowers. Some of those pink flowers and all of the white will
breed true for flower color, but the majority, if self-pollinated, will continue
to separate out. As a result, it is impossible to save hybrid seed.
[Dustin Blakey standing in a tomato garden] Vegetables aren't the only plants
that are hybrids. We also have hybrids in ornamentals, too. [Dustin shows a
hybrid petunia and vinca plant] For example this petunia here is a hybrid plant,
as is this vinca growing right here.
[Cartoon – Can't decide? Drawing of a man with a question mark above his
head] If you're wondering which is better, that's largely going to be a decision
you have to make yourself. [Picture of a corn field] For most commercial
producers the benefits of hybrid plants more than make up for the extra cost of
the seed, but home gardeners mostly are concerned with taste and novelty, but no
expense.
[Picture of different types of hybrid tomatoes] There's not a lot of economic
incentive for breeders to create good hybrid version of most novelty crops like
these unusual tomatoes, so if you like to stray off the beaten path you will
most likely be growing open-pollinated cultivars.
[Picture of a boy eating a slice of watermelon] Flavor is more complicated.
Partly one's personal taste comes into play, but there is nothing inherently
superior about a plant that happens to be labeled an heirloom.
[Dustin Blakey standing in a tomato garden tasting a tomato as camera man
Jesse Bocksnick laughs ] That could stand to ripen a little more.
[Picture of a plant with Septoria Leaf Spot] Many heirlooms do taste great,
but there is a good chance they are lower-yielding and more fickle about their
care.
[Dustin Blakey standing in a tomato garden] If you have any questions about
the benefits of hybrids or have an interest in heirloom tomatoes, or have
questions about gardening in general, contact your County Extension Office.
[Questions? Contact your Extension Office U of A University of Arkansas
Division of Agriculture dblakey@uaex.edu]
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