Agriculture Reference
In-Depth Information
cultivars need to have oil that is high in erucic acid con-
tent. The determination of most quality traits is based in
their genes (i.e. is genetic) although the growing condi-
tions of soil type, irrigation management and nitrogen
application can all have large influences on the level
at which these characters are expressed and hence on
the final crop quality. Similarly, mechanical damage
(particularly in vegetables and fruits) and crop disease
can both greatly reduce the overall quality of the product
irrespective of what the end use will be.
Determining '
desirable quality
' characteristics can be
difficult and requires close integration of the breed-
ing team with end-users and processors. Within some
countries (e.g. the United States) government authori-
ties have laid rules for quality standards (e.g. USDA #1
produce). In these cases it is often easier to set standards
for the acceptable level of quality required from breed-
ing lines. Caution however needs to be exercised since
it is unlikely that these standards will remain constant
through time, indeed they may change dramatically
even before the new cultivar is even released!
acceptance) would require large quantities of grain and
considerable time. Obviously both these would be
impossible in all but the very last stages of a breed-
ing scheme. The basic features of any effective quality
assessment in a plant breeding programme is that they
should be
quick
,
cheap
and
use very little material
.
These three criteria are important because:
•
A plant breeding programme will involve screen-
ing many thousands of breeding lines each year or
growing cycle.
A plant breeder is often working against time. Many
quality traits are assessed post-harvest and it is often
important to make selection decisions quickly, before
large-scale quality is determined.
•
In most stages of a plant breeding scheme there are
only limited amounts of material available for testing.
It is often the propagative parts of the plants (seeds
or tubers) that are used for testing and so a further
complication is that many of the quality tests available
are destructive of the very parts of the plant that are
required to be grown to provide the next generation
for selection.
•
Testing for end-use quality
It is clear therefore that it is important to determine
at what stage in the breeding scheme to begin various
quality screens. Obviously, quality evaluation should be
included as early in the selection process as possible to
avoid discarding some potentially high quality breeding
lines. However, often this decision must be based on
the cost of test, volume of material needed, accuracy of
the test and the importance of the quality trait for the
success of any new cultivar.
Taste panels (groups of experienced [or sometimes
inexperienced] people who assess the food quality of
new products) are often used. It is, however, impossible
to compare more than a few types or breeding lines
with a taste panel. These tests must also include some
standard control lines, for comparative purposes, which
further limits their potential when more than a few lines
are to be tested.
Most other quality assessments are, at best, estimates
of what will happen in the '
real world
'. They tend to
be mini-reconstructions of parts of a larger scale com-
mercial process or operation. When carrying out these
assessments great care should be taken to ensure that the
test follows as best as can be achieved the actual process
that will happen in industry. It is therefore essential that
If new cultivars are released which have special qual-
ity characters there may be justification, and economic
merit, in introducing this as a '
specialty
' product even
if overall yielding ability is not high. This would be
justified if economic returns were sufficiently high to
overcome the deficiencies in total yield. It should also
be noted that competitors and other breeders will, of
course, be quick to notice the market opportunity that
has been opened and will focus on rapidly supersed-
ing such introductions, perhaps overcoming any of the
obvious defects present in the original cultivar (e.g. pink
grapefruit).
It is usually difficult (and most often impossible) to
carry out an exactly similar processing operation on a
large number of breeding lines. For example, in order
to obtain the true quality potential of a new potato
line with regards to French fry production (taking into
account quality of end product, oil uptake, ease of
processing, etc.), it would be necessary to produce
several hundred tons of tubers and make French fries
from them in a commercial processing plant. Similarly,
in order to determine malting potential of barley for
whisky (including all operations through to consumer
