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market-farming - Re: [Market-farming] Peppers Crossing

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  • From: "Bill Shoemaker" <wshoemak AT inil.com>
  • To: "Market Farming" <market-farming AT lists.ibiblio.org>
  • Subject: Re: [Market-farming] Peppers Crossing
  • Date: Tue, 9 Mar 2004 08:14:05 -0600

There seems to be a lot of worrying about peppers cross-pollinating. It's
not really a serious problem unless you are saving seed, and then it's only
an annoyance. It isn't that difficult to protect the pollination process.
Let me review a few things.

First, if a hot pepper and a sweet pepper cross pollinate, the sweet peppers
will NOT become hot. The genes expressing the trait for heat will not impact
this year's crop. They will only be found in the seed, not in the fruit of
the sweet pepper. If the sweet pepper turns out to be hot, it's because the
seed had already been contaminated in the previous season, when the flowers
on the parent plant were pollinated.

Second, peppers are self pollinating plants. That means that each flower can
pollinate itself. It does not need pollen from another flower or another
plant to successfully set seed and produce a fruit. Because the pollen in a
flower is viable and is just adjacent to the stigma of the flower, in most
cases, each flower pollinates itself. However, unlike tomatoes, pepper
flowers have a very open habit. The anthers, which carry the pollen, project
outward and the petals do not shield the stigma. So pollen will fly about,
leading to some potential for out-crossing. Even further, bees will work on
pepper flowers, carrying pollen from one plant to another. Both of these
circumstances can lead to cross-pollination. To prevent cross pollination
and to preserve seed and varietal purity, you need to prevent pollen moving
from variety to variety. Cages which constrict air movement and insect
passage are generally adequate. Another approach is to use spun-bonded row
covers over large hoops. The peppers can be grown underneath. They can
pollinate themselves and each other as long as they are all the same
variety. The seed gathered from the fruit of those plants will be
representative of that pepper variety. Keep in mind, particularly with
open-pollinated plants, that they are not necessarily 100% pure. There are
many "hidden" genes which can emerge within an O.P. variety after being
latent for a long time. If the gene represents a bad trait, those plants can
be culled out. If it represents a good trait, maintain it. Also, mutations
can occur spontaneously and quite naturally in the field. A number of
natural sources for mutation occur, including ultra-violet light. So if
variation emerges, it does not mean you had cross-pollination. If a lot of
variation occurs over many different plants from a seed batch, and you
aren't quite confident in your isolation (caging) practices, you might have
accidently allowed cross-pollination.

I hope this helps some of you who are saving seed and trying to maintain
varietal purity. With peppers, it's not too difficult, but it can demand
some of your time. Remember, even with no protection, only about 5%
outcrossing occurs, mostly due to insects. So with a proper barrier, pepper
variety purity can be relatively easy to maintain.

Bill Shoemaker
Sr Research Specialist, Food Crops
Univ of Illinois - St Charles Hort Research Center


>Has anyone tried using barriers to keep varieties seperate? Such as
>hoop-houses with filters on the ventilation system. I suppose to filter
the
>pollen you would need expensive HEPA filters.
>
>What about spun-bonded row covers, I hear that they have to be removed to
>get pollenation to take place, mayeb they could be used to keep foreign
>pollen out.
>
>Any ideas?
>-Paul Bock
>Stone Gully
>
>
>"Pepper varieties need to be planted AT LEAST 1,500 feet from one another
>or they will cross. "
>
>
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