 |
Tremendous amount of diversity is in
evidence in one generation of corn. |
When
teaching seed saving, I often rely on allusions to animal
reproduction because most of my students have some experience with
that and it helps make the point easily. However, one concept that
doesn't lend itself well to such conversion is the need for
population size in seed saving.
In
the inventory that SLOLA has garnered over the last several years, we
have enormous variety of seeds, many different beans, some different
corn, a ton of squash varieties and so on. This is wonderful and I'm
sure we need to consider saving all these varieties locally. But I
don't think we can and the reason is population size.
The
genetics of open pollinated seeds are very different from hybrid
seeds or animals. The seed we call Yugoslavian Red Lettuce is not
'pure' like we think of when we think of genetic purity (like we sit
around and contemplate that on a weekly basis). The genes in open
pollinated seeds have a certain amount of 'flex' in them. You get the
typical Yugoslavian Red Lettuce from the vast majority of your
plants, but lurking under those frilly red leaves is a foundation of
other genetic code. You don’t see it normally, but every so often
a 'one off' pops up. If you are saving seeds for Yugoslavian Red,
you don't collect seeds from the one off – if you like the one off,
you save seeds of it separately from the Yugo Red and label it Yugo
Not Red or Hungarian Red, just something different.
This
variability is a great strength for seeds. It allows for adaptation
to meet threats from insects or disease – or even drought. Perhaps
from a garden full of Yugoslavian Red only a few plants survive the
drought, but that's better than none. Or perhaps only one or two
don't get the disease, but that's better than losing everything –
and this is part of our desire to save these varieties: they survive
under less than ideal conditions and they can meet threats to our
food security better than any lab-created hybrid – especially GMOs.
However,
our seed library – and I would imagine MOST seed libraries – are
in danger of compromising this variability in our open pollinated
varieties. They are not doing it intentionally, but it might well be
happening despite their best intentions. I do believe SLOLA has
inadvertently gone down this path somewhat and I hope we can refocus
our efforts.
Back
in the beginning I asked us to consider saving only seeds of some 150
varieties of vegetables. No more. I did this because I wondered at
the time if we could really save seeds for several hundred different
varieties for a period of time. I asked several times for folks to
list the seeds they wanted saved – the varieties in their gardens
they couldn't live without and got very little response. I went
along with the flow and we allowed SLOLA's inventory to bulge with
varieties from donations and gifts. Now I am convinced we cannot
save all these different varieties of seed and we must return to a
figure nearer 150 varieties. The reason is population size
The
variability shown in open-pollinated seeds means to have a viable
representation of all the different traits that make Yugoslavian Red
Yugoslavian Red means there must be many plants each year from which
the seeds are saved in order to keep that variety as viable as it has
been for all these many different generations.
To
save seeds from one plant for several years stands to lose some of
those unseen genetic traits that make it such a good competitor
against insects and disease in our gardens – might even result in a
poorer quality lettuce over time. To save seeds and ensure the
viability of our varieties over time, we must adopt policies that
encourage larger population size of each variety. This might mean
limiting our offerings to three lettuces, several tomatoes and so on.
I
am going to ask our Best Practices committee for a list of varieties
we on which we can focus and narrow our offerings towards those
varieties. We still need knowledgeable gardeners create lists of the
best varieties for Los Angeles and we must strive to have seeds from
many more plants per variety to keep the diverse genetics present.
Here
are a few guidelines, followed by simple definitions, towards which
we need to work:
|
Breeding Style
|
Minimum Populations
|
Examples (but not complete!)
|
Severe
inbreeders
|
10
|
tomatoes,
lettuce and regular beans for the most part
|
|
Moderate
inbreeders
|
40
|
all
the other night shades, including eggplants and peppers; other
bean family members like peas and other beans
|
|
Outbreeders
in general
|
80
|
the
cabbage family
|
|
Sensitive
Outbreeders
|
200
|
corn,
carrots and onions, these are 'sensitive' to a phenomena called
'inbreeding depression' which causes a severe reduction in plant
performance in just a few generations – corn is considered the
most sensitive of all
|
|
Insensitive
Outbreeders
|
10
to 20
|
not
sensitive to inbreeding depression, specifically Cucurbits,
including squashes, cucumbers and melons
|
Inbreeding
is a term applied to plants that will pollinate themselves (male and
female flower parts exist in each flower of the plant and can
self-pollinate before the flower even opens). Outbreeding apples to
plants that must be pollinated by other plants to produce viable
seed. These definitions are much simplified for this discussion
only. If you like to learn more about this, Carol Deppe's book
“Breed Your Own Vegetables” offers one of the most thorough and
easily digestible definitions of these terms.
I
am not proposing a drastic change. For the library, this means we
will be less diligent about the return of seed for some varieties
than for others – we are on a learning curve anyway, so we will
need to realize there are some varieties that will be lost from our
inventory and we will not be concerned with them. Over time, the
varieties that are truly SLOLA varieties will change into an
inventory we can manage more effectively. Some of this will be
through natural attrition. Others will be actively cultivated into
predominance by the Best Practices Committee and other active
members.
What
we need to do most of all is educate members about the minimum
populations we are trying to achieve. Remember, it is the collective
total of all the seed returned that make minimum population size –
so if Megan grows Nutribud Broccoli (one of my favorites) and collects seeds from 6 plants,
Linda does the same collecting from 4 plants, Albert collects from 7
plants and I collect from 3 we've met our minimum population of 20.
All seed goes together to make the minimum population.
This concept is very important and central to
our mission. Thank you for taking the time to read this. I hope it makes sense to you. If not, please let me know as I wish this to be clear; it is important to the long-term viability of the seed library and our seeds.
david
