Cereals processing technology

crop free from weeds and diseases, especially mildew, is important in achieving
a high yield of quality grain.
2.2 Varietal selection
Cereal production methods 17
The contribution of new cereal varieties to the profitability of grain production is
well recognised. The prime objective of plant breeders from the outset has been
to develop high yielding varieties, with good disease resistance against the major
cereal pathogens. This continues to be a major aim of current breeding
programmes, although increased attention is now being directed towards
improving grain quality to meet specific market requirements.
In wheat, and to a lesser extent barley, improved grain yields have been
achieved through selection of short strawed varieties. Old and new varieties of
cereals differ very little in the amount of total dry matter accumulated during the
growing season, but selection for a higher Harvest Index (HI) has resulted in a
greater proportion of this biomass being accumulated in the grain. The HI of
varieties in cultivation during the period 1930–40 was around 30%, compared to
between 50 and 55% for present day varieties (Austin et al. 1980). Further
agronomic advances have been achieved with selection for improved standing
power, whilst increased resistance to grain shedding and sprouting have
contributed significantly to advances in wheat breeding.
Breeding new varieties with improved resistance to the major cereal diseases
has always been a key objective for plant breeders. Before the introduction of
broad spectrum systemic fungicides in the late 1970s, genetic resistance was
often the only defence mechanism available to growers and was often the most
important factor to be considered when choosing a variety. Good varietal
resistance remains an important consideration, even within current husbandry
systems in which routine applications of two or three fungicides is commonplace
during the growing season. Poor genetic resistance can lead to a rapid epidemic
build up of disease, which may prove difficult and expensive to control leading
to a detrimental effect on yield and quality.
The suitability of wheat or barley for different end uses is partly under
genetic control, although varietal differences can be modified by husbandry and
weather conditions. Characteristics such as the endosperm texture of wheat and
the malting potential of barley is entirely under genetic control, while quality
parameters such as specific weight are influenced to a greater extent by
husbandry and climate. Considerable advances have been made in developing
varieties with improved quality attributes through a better understanding of their
molecular basis. At the same time market needs have become more clearly
defined which is likely to lead to better targeting of new varieties for specific
markets in the future.
New varieties must demonstrate that they are distinct in their genetic makeup,
uniform and stable in their characteristics and have value for cultivation and
use before they are added to the UK National List. Further evaluation with and