Principles of Plant Genetics and Breeding

Purpose and expected outcomes
The ultimate goal of the plant breeder is to be able to identify a superior genotype that can be released as a new cultivar
to farmers for commercial production. To arrive at this goal, many experimental genotypes of high genetic
potential are evaluated for performance capabilities under various environmental conditions, over several seasons
and years, and at different locations. Detailed records are compiled and analyzed to help in the decision process. The
breeding materials are evaluated by using appropriate statistical tools that entail design of the trials, collection of
data, analysis, and interpretation of results. This calls for an understanding of how genotypes interact with the
environment and of the field plot technique. After studying this chapter, the student should be able to:
1 Discuss the concept and role of genotype × environment interaction in plant breeding.
2 Describe the field plot technique in plant breeding.
3 Discuss the process of crop registration.
Purpose of performance trials
As indicated in all the breeding schemes discussed in this
book, the breeder conducts performance or field trials of
the advanced generation of the materials developed in a
breeding program, primarily to identify a genotype to be
released as a cultivar to producers. In a sense, these tests
or field trials are designed to forecast the performance of
the genotype to be released as a cultivar. These trials are
usually called yield trials because yield is usually the most
important trait in a breeding program. Breeding programs
are frequently undertaken to address “secondary”
traits (disease resistance, early maturity, high seed protein,
etc.). If these traits are successfully transferred but
the genotype has poor yield, it would not be released
as a cultivar. The field trial also enables the breeder to
collect data about the characteristics of the potential
cultivar for other uses (e.g., registration of the cultivar).
It is the primary source of information for the breeder to
use in the decision-making process of cultivar release.
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Performance evaluation
for crop cultivar release
The breeder is not only concerned about the level of
yield of the cultivar but also about the stability of yield.
Consequently, stability analysis is often part of the performance
evaluation of genotypes prior to cultivar release.
The concepts of adaptation and yield stability analysis
are further discussed later in this chapter.
Kinds of field trials
There are two basic kinds of field trials conducted in
plant breeding – breeders’ trials and official trials.
Breeders’ trials
These trials are conducted for the primary purpose of
evaluating the performance of the final set of genotypes
(advanced generations in a breeding program) to allow
the breeder to make a decision as to which genotype to
release as a cultivar. Some breeders conduct these trials