Agriculture Reference
In-Depth Information
plant breeding. Genetics is an ever developing subject
but knowledge and understanding that is particularly
useful will include single gene inheritance, popula-
tion genetics, the likely frequencies of genotypes under
selection and the prediction of quantitative genetic
parameters - all of which will underlie decisions on
what strategy of selection will be most effective.
Pathology
A major goal of plant breeding is to
increase productivity and quality by selecting superior
genotypes. A limiting factor in economic production is
the impact of pests and diseases. Therefore developing
cultivars, which are resistant to detrimental pathogens,
has been a major contributor to most cost effective pro-
duction with reduced agrochemical inputs. Similarly,
nematodes, insect pests and viruses can all have detri-
mental effects on yield and/or quality. Therefore plant
breeders must also have knowledge of
nematology
,
entomology
and
virology
.
Weed Science
The response of a genotype to compe-
tition from weed populations will have an effect on the
success of a new cultivar. Cultivars that have poor plant
establishment, or lack subsequent competitive ability,
are unlikely to be successful, particularly in systems
where reduced, or no, herbicide applications are desir-
able, or their use is restricted. Similarly, in many cases
genotypes respond differently, even to selective herbi-
cides. Herbicide tolerance in new crops is looked upon
favourably by many breeding groups, although culti-
var tolerance to broad-spectrum herbicides can cause
management difficulties in crop rotations.
Food Science
Increasing end-use quality is being
identified as one of the major objectives of all crop
breeding schemes. As most crop species are grown for
either human or animal consumption, knowledge of
food nutrition and other related subjects is important.
Biometry
Managing a plant breeding scheme has
aspects that are no different from organizing a series
of large experiments over many locations and years. To
maximize the probability of success it is necessary to
use an appropriate experimental approach at all stages
of the breeding scheme. Plant breeding is continually
described as '
a numbers game
'. In many cases this is
true, and successful breeding will result in vast data
sets on which selection decisions are to be made. These
decisions often have to be made during short periods,
for instance between harvesting one crop and planting
another. Therefore, plant breeders are required to be
good
data managers.
Agronomy
It is the aim of crop breeders to predict
how newly identified genotypes will perform over a wide
range of environments. This will require research into
agronomic features that may relate to stress tolerance,
such as heat, drought, moisture, salinity, and fertility.
These experiments are essential in order that farmers
(the primary customer) are provided with the optimal
agronomic husbandry parameters, which will maximize
genetic potential of the new variety.
Molecular Biology
Advances in molecular biologi-
cal techniques are having an increasing role in modern
plant breeding. Molecular markers are increasingly used
by plant breeders to help select (indirectly and directly)
for characters that are difficult to evaluate in the labora-
tory, or are time consuming, or expensive to determine
accurately on a small plot scale. Genetic engineering and
other tissue culture operations are becoming standard in
many plant breeding schemes and it is likely that further
advances will be made in the future. Knowledge of all
these techniques and continued awareness of ongoing
research will be necessary so that new procedures can be
integrated into the breeding scheme where appropriate.
Production
The contributions that farmers, and
other growers, have made to varietal development
should never be underestimated. It also should be noted
that growers are the first customers for plant breeding
products. The probability of a new cultivar being suc-
cessful will be maximized (or at least the probability
of complete failure reduced) if growers and production
systems are considered as major factors when designing
breeding systems.
Management
There is a need to manage people,
time and money. It has already been stated that plant
breeding is a multidisciplinary science and this means
being able to integrate and optimize people's effort to
effectively use breeders' time. The length of most breed-
ing programmes means that small proportional savings
in time can be valuable and it hardly needs emphasizing
that breeding needs to be cost effective and therefore the
cost of the programme is always going to be important.
Communication
Most varietal development pro-
grammes consist of inputs from more than one scientist
and so it is necessary that plant breeders are good
communicators
. Verbal and written communication of
results and test reports will be a feature in all breeding
schemes. Research publications and grant proposals are
of major importance, particularly to public breeders, if
credibility and funding is to be forthcoming. Finally,
