Plant Biotechnology and Genetics: Principles, Techniques and Applications

could become a plant variety, and the final stages of variety development will begin.
Several additional things must now be accomplished:

1. Additional selection among inbred lines must be done. This selection will be among a
   decreasing number of lines that are increasingly elite. This selection may result in the
   complete elimination of all lines from a given cross—perhaps in favor of keeping
   additional lines from a cross that turned out more favorably.


2. Varietal purity must be monitored and maintained.


3. An inbred line may need to meet industry established standards for registration as an
   “official” plant variety. These standards include descriptions, uniformity, uniqueness,
   and sometimes merit in relation to competing varieties. Increasingly, plant variety
   protection, which restricts unauthorized use of the variety, is sought in addition
   (or as an alternative) to variety registration.


4. Seed must be increased to a level where there is enough to sell or to distribute to a
   seed producer.

These requirements may vary among different countries, states, or provinces, and they
are often unique among different species. However, the general principles are the same,
and so is that fact that they are often addressed simultaneously. Table 3.1 lists the typical
final steps in the birth of a plant variety, and how each of the abovementioned requirements
might be met.

TABLE 3.1. StepsaInvolved in Final Stages of Variety Development in a
Self-Pollinated Species

Step Description Activities

Progeny rows Single row, nonreplicated Select promising rows, rogue off-
types, bulk seed from characteristic
plants
Home tests One site, two replicates, 1 year: material
from home programþstandard check
variety

Detailed selection, may include
characters such as quality that
require increased amounts of seed;
rogue off-types and bulk remaining
seed
Preliminary
tests

Three sites, three replicates, 1 year:

material from home

programþstandard check

varietyþother current varieties and

possibly lines from collaborating

breeders

Detailed and final selection of several

lines to enter into variety registration

trials; identify defining characters,

rogue off-types, bulk seed

Breeders’ seed
rows

Nonreplicated plots grown in isolation to

increase seed for supply of potential

variety

Identify defining characters, rogue off-

types, bulk seed

Registration
tests

Six sites, four replicates, 2 years:

cooperative tests that include several

best lines from each

breederþstandard check varieties

Selection of lines to support for
registration (often competitive
among breeders); apply for plant
variety protection on probable
winners (year 2)
aThese steps must address several requirements simultaneously: testing and selection, varietal purity, registration
and/or protection, and seed increase and distribution.

68 PLANT BREEDING