Principles of Plant Genetics and Breeding

Registered seed
Registered seed is produced directly from breeder seed
or from foundation seed. It is the source of certified
seed. It is often grown by farmers under contract with a
seed company. The material is subject to inspection in
the field as well as harvested seed. Farmers may commercially
plant this seed.
Certified seed
Certified seed may be produced from foundation, registered,
or certified seed. It is grown in isolation under
prescribed conditions for the crop such that it meets the
genetic identity and purity of the cultivar required for
approval by the certifying agency upon both field and
seed inspection. This class of seed is that usually available
for planting by producers.
Maintaining genetic identity of the breeder seed
Properties of the breeder seed
The breeder must increase the original seed to have
enough to store and supply to growers in the commercial
seed multiplication chain. This seed (breeder seed)
must be of high purity, quality, health, and uniformity.
1 Purity. The seed must be free from contamination
from other cultivars of the same species, as well as
other foreign materials (e.g., weed seeds, pollen).
The breeder seed is the most authentic and genetically
pure seed. To obtain this high level of purity, the
seed must be produced in a location distant from all
sources of possible contamination and harvested and
processed with care (using clean equipment).
2 Quality. High quality seed is one that is fully mature
and produced under an optimal environment so that
all the traits of the cultivar are optimally expressed. It
should be harvested at optimal moisture content.
3 Health. The seed should be free from diseases and
damage from insects. This is difficult to achieve, especially
if the disease is seed borne.
4 Uniformity. Cultivar uniformity depends on the kind
of cultivar that was bred. Clonal cultivars, hybrids, and
inbred lines can be uniform to a great extent; synthetics
and other open-pollinated cultivars are less uniform.
Causes of loss of genetic purity of seed
Genetic deterioration of the breeder seed may arise from
several sources.
SEED CERTIFICATION AND COMMERCIAL SEED MULTIPLICATION 441
1 Mechanical admixture. Failure to clean planting,
harvesting, and processing machinery and equipment
used in seed production may result in the physical
transfer of seeds of one cultivar to another. When
the contaminated cultivar is planted, more of the
offending seed will be produced to further pollute
the genetic purity of the cultivar of interest (unless
the offending genotype has distinct morphological
features that would enable the breeder to readily
rogue them out before harvesting).
2 Natural outcrossing. Natural outcrossing by wind
or insects may occur where the new cultivar is planted
close to another cultivar. As previously indicated, the
breeder seed should be planted in isolation to avoid
or decrease the chance of natural outcrossing with
other cultivars in the vicinity.
3 Mutations. Spontaneous mutations may arise during
multiplication of seed.
4 Growing in area of non-adaptation. Growing the
cultivar in an area to which it is not adapted could
induce developmental variations.
Prevention of loss of genetic purity
There are a number of strategies to prevent the loss of
genetic purity in breeder seed.
1 Plant in isolation. Planting the breeder seed in isolation
reduces the opportunities for outcrossing.
2 Rogue out off-types. All atypical material should be
rogued out of the field before harvesting.
3 Plant only in areas of crop adaptation. This reduces
the incidence of developmental changes.
4 Enforce quality control measures (e.g., sanitation,
cleaning of equipment).
Concept of seed certification
Seed certification is a legal mechanism established to
ensure that pedigreed seed produced by a plant breeder
reaches the public in its highest quality, with its original
genetic identity, and with the highest genetic purity. A
certified seed is required to be identified by a label that
attests to the quality of the product by guaranteeing its
genetic constitution, level of germination, and results of
seed analysis. Certification is conducted by certifying
agencies according to prescribed guidelines for the crop
and the Association of Official Seed Certifying Agencies
(AOSCA) (most certifying agencies are members of this
agency). It includes field inspection and seed inspection
of crops grown under prescribed conditions. Following