Principles of Plant Genetics and Breeding

292 CHAPTER 16
Generation
Year 1 P 1 × P 2
Year 2
Year 3
Year 4
Year 5
Years 6–7
Year 8
Years 9–11
F 1
F 2
F 3
F 4
F 5–F 6
F 7
F 8–F 10
Figure 16.4 Generalized steps in breeding by pedigree selection.
between rows by first identifying superior rows
and selecting 3–5 plants from each progeny to
plant the next generation.
Year 5 By the end of the F 4 generation, there should be
between 25–50 rows with records of the plant
and row. Grow progeny of each selected F 3 .
Year 6 Family rows are planted in the F 6 to produce
experimental lines for preliminary yield trials
in the F 7 . The benchmark or check variety is a
locally adapted cultivar. Several checks may be
included in the trial.
Year 7 Advanced yield trials over locations, regions,
and years are conducted in the F 8 –F 10 genera-
Number
of plants
50–100
2,000–5,000
200
100
25–50
15
5–10
1
Action
Select parents and cross
Bulk seed; space plant for
higher yield
Space plant for easy
visual selection
Select and plant in spaced rows
Identity superior rows; select 3–5
plants to establish family in progeny
rows
Establish family progeny rows;
select individual plants to advance
each generation
Conduct preliminary yield trials;
select individual plants to advance
Conduct advanced yield trials with
more replications and over locations
and years
Cultivar release
tions, advancing only superior experimental
material to the next generation. Ultimately,
the goal is to identify one or two lines that are
superior to the check cultivars for release as a
new cultivar. Consequently, evaluations at the
advanced stages of the trial should include superior
expression of traits that are deemed to be of
agronomic importance for successful production
of the particular crop (e.g., lodging resistance,
shattering resistance, disease resistance). If
a superior line is identified for release, it is put
through the customary cultivar release process
(i.e., seed increase and certification).