Principles of Plant Genetics and Breeding

of spread, life cycle, and most suitable environment).
Sometimes, the pest must be controlled to avoid interfering
with the breeding program.
Statistics
Plant breeders need to understand the principles of
research design and analysis. This knowledge is essential
for effectively designing field and laboratory studies
(e.g., for heritability, inheritance of a trait, combining
ability), and evaluating genotypes for cultivar release
at the end of the breeding program. Familiarity with
computers is important for record keeping and data
manipulation. Statistics is indispensable to plant breeding
programs. This is because the breeder often encounters
situations in which predictions about outcomes,
comparison of results, estimation of response to a treatment,
and many more, need to be made. Genes are not
expressed in a vacuum but in an environment with
which they interact. Such interactions may cause certain
outcomes to deviate from the expected. Statistics is
needed to analyze the variance within a population to
separate real genetic effects from environmental effects.
The application of statistics in plant breeding can be as
simple as finding the mean of a set of data, to complex
estimates of variance and multivariate analysis.
Biochemistry
In this era of biotechnology, plant breeders need to be
familiar with the molecular basis of heredity. They need
to be familiar with the procedures of plant genetic
manipulation at the molecular level, including the
development and use of molecular markers and gene
transfer techniques.
The plant breeder as a decision-maker
Modern plant breeding is a carefully planned and executed
activity. It is expensive and time-consuming to breed a
new cultivar. Consequently, the breeder should make
sound decisions, some of which are scientific (e.g., type of
cultivar to breed, germplasm to use, breeding methods),
whereas others are socioeconomic or even political.
Some of the key specific decisions in a plant breeding
program are discussed next. Because these elements are
interdependent, the breeder should integrate the decisions
to form a harmonious and continuous sequence,
from inception to cultivar release. A breeder should have
good management skills. Experts have identified four
dimensions of management as follows:
THE ART AND SCIENCE OF PLANT BREEDING 27
1 Organization design. The breeder should plan the
physical structure of the project as pertains to personnel,
equipment, field, greenhouse, nurseries, and
other needs.
2 Planning and control. Planning entails defining
clear objectives and strategies for accomplishing
them, while control entails establishing an effective
system of data management (collection, storage,
retrieval, processing) to provide reliable and accurate
information for decision-making at all the steps in the
plant breeding project.
3 Behavioral process. The team engaged in the
project should work and relate well with each other
(teamwork).
4 Decision-making. The plant breeder is a decisionmaker.
Critical decisions are made throughout the
breeding program. This is the most important aspect
of management in a breeding project. It entails first
identifying the problem, then analyzing it to find the
root causes and effects. Next, the breeder should
develop alternative solutions, evaluate them, and then
choose and implement the most desirable solution.
Some of the specific decisions made in a breeding project
are as follow.
Breeding objectives
The breeder must first define a clear breeding objective
and ascertain its importance, feasibility, and costeffectiveness.
As previously noted plant breeding is
expensive to conduct and hence a breeding objective
should be economically viable or of significant social
benefit. Furthermore, every problem is not amenable
to genetic manipulation through breeding. Breeding
objectives vary among crops (see Part II). Where multiple
objectives are identified, they should be prioritized.
Keeping in close touch with crop producers and consumers
will allow the breeder to gain insight into what
ameliorations are likely to be acceptable to them.
Growers will not grow what they cannot sell. Long-term
plant breeding programs are usually formulated to
address the key problems that producers face.
Germplasm
The plant material used to initiate a breeding program is
critical to its success. The parents used in a cross should
supply the gene(s) for the trait of interest. Sometimes,
germplasm may have to be imported for developing
new cultivars or evaluated for adaptation to a specific
environment. Advanced breeding programs maintain