What is an OPV? - The Gaia-Movement

What is an OPV?
Open-pollinated varieties, or OPVs, refer to
varieties of maize, sorghum or millet. OPVs are
broad populations of many related plants. The
pollination of the plants in the seed field is not
controlled, other than growing the crop
separate from other crops, and so the seed of an
OPV is genetically diverse, but related. Thus,
an OPV can be thought of as an extended family
with all members having similar related
characteristics, yet there will still be some
extremes within the family. This means that
the crop of an OPV will not be highly uniform,
like a hybrid. For example, the crop will vary
in plant height, the color of the silks might
show differences, and the cobs will not all be of
the same size and shape, while the plants will
also mature at different times.
Farmers who have grown maize and retained
the seed from year to year are growing OPVs of
their own selection. These are sometimes called
“land races” and they may be well adapted to
the farmer’s environment. However, improved
OPVs are available on the market. These have
been developed to be drought tolerant, disease
resistant, and well adapted to the areas for
which they are recommended. They are sold as
certified open-pollinated seed with a
particular name. There may be many improved
OPVs available and thus the farmer needs to
choose the one recommended for his/her area.
What are the advantages of growing OPVs?
• The cost of the seed of OPVs is not as high
as that of hybrid seed.
• More money can then used for buying
fertilizer and pesticides.
• OPVs represent an economic option when
hybrid seed and fertilizer prices are high
relative to the price of grain.
• Seed can be recycled (i.e., retained after
harvest for planting in the next season)
with minimal loss in yield. This is unlike
recycled hybrid seed, which suffers as
much as 30 % loss in yield. Farmers who
cannot readily obtain seed can therefore
maintain their own sources of seed.
• If the farmer is situated in a low potential
environment and cannot afford extra inputs
to justify the cost of hybrid seed, OPVs are
a good alternative.
• As OPVs are more variable in flowering
dates and peak drought stress is most severe
during flowering, this variation can at
times offer more stable yields than do
more uniformly flowering hybrids. This is
because some of the plants might be better
able to survive adverse conditions.
The disadvantages of growing OPVs include:
• The yield potential of OPVs is typically
10-25% lower than that of hybrid seed,
although this often depends on the
management and production environment of
the farm.
• If a farmer is situated in an area with high
yield potential and has access to fertilizer
and pesticides, then growing OPVs will
reduce his profit margins. This is because
his potential yield will not be as high as
when growing hybrids.
• OPVs may not be uniform in color, maturity
and other plant characteristics, leading to
less aesthetically pleasing harvests. This
could potentially impact the price of the
grain if it is sold.
• This lack of uniformity may lead to
difficulties in the carrying out of certain
operations such as harvesting, especially
when using combine harvesters.
Farmers who live far from retail shops can
recycle seed from certified OPVs for a maximum
of three years without significant yield loss if
they are careful to avoid contamination of
pollen from neighboring fields.
When recycling open-pollinated varieties the
following should be remembered.

• First, grow an OPV that is recommended for
your area and obtain certified seed from a
reputable dealer.
• Manage your fields well, practicing
conservation agriculture, using manure or
fertilizer or both, and control weeds and
pests.
• Grow your crop at least 100 meters away
from other maize fields, or sow your maize
three weeks earlier or later than nearby
crops, so that it flowers at a different time.
In this way you will ensure that
unnecessary contamination of pollen does
not occur.
• If you cannot isolate by time or distance as
outlined above then you should harvest
from the middle of the field to minimize
contamination and the field should be at
least about one hectare in size.
• Inspect your field before flowering and
remove any plants that look very different
from the others, especially if they are very
short or very tall, or if they are diseased.
• When harvesting for seed, choose only the
best cobs from the best looking plants that
are near the centre of the field. At least 500
cobs should be harvested, and harvesting
should take place when the husks are dry.
Select cobs that are uniform, free of disease
and have the desired grain quality.
• The cobs should be shelled, dried in the sun
and then stored under appropriate
conditions, i.e., in a dry, protected place.
• Shelling should be carried out when the
grain is dry. This is usually when the grain
has reached 13 % moisture content. (To test
this, mix 100 seeds with one gram of salt
and leave in a sealed bottle. If after five
minutes salt feels moist then cobs need more
drying.)
• Once the seed is dried to 13 % moisture it
should be treated with insecticides and
fungicides against pests.
• Seed should be stored in a cool, dry place,
away from sunlight and not used for
consumption by animals or humans. Ensure
that rodents do not have access to the seed,
as they can destroy the seed in a very short
space of time.
• OPVs may be recycled for 3 seasons before
buying new certified seed.
Seed production of open-pollinated varieties
There are three stages in the production of seed.
The first stage is the production of breeder’s (or
pre-basic) seed. This is carried out by the
originator of the variety, usually called the
breeder. Breeder’s seed is produced in small
plots where a breeder can monitor the plants to
ensure that as many off-types as possible are
eliminated.
The second stage is the production of
foundation or basic seed. The foundation seed
is produced by breeders or seed companies and
represents the first increase in the breeder’s
seed, in order to obtain sufficient quantities for
certified seed production.
The third stage is the last stage in seed
multiplication, and is called certified seed
production. Seed companies contract farmers to
produce certified seed. Farmers need to first
register with the government and the seed
services as a seed grower to be able to grow
certified seed. The seed is grown under
specified conditions to ensure standards. Before
being labeled and sold as certified seed,
laboratory tests are carried out to ensure that
the seed is viable and healthy and meets the
quality as described on the label.
This fact sheet was prepared as part of the IRRI-CIMMYT alliance - Cereal Knowledge Bank
(knowledgebank.cimmyt.org) • Developed with input from A.L.MacRobert, P.Kosina, J. Jones • 2007