5.5.1 Cereals
The cereals, which all belong to the Gramineae or the grass family, are
one of the most important sources of carbohydrates in the human diet.
Some of the more important cereal crops are listed in Table 5.9. Wheat,
rice and maize are by far the most important cereal crops on the basis of
world-wide tonnage and well over three hundred million tons of each are
produced annually. However, each cereal species is adapted to grow in a
particular range of climatic conditions although plant breeding pro-
grammes have extended the ranges of several of them. The common
wheat is the major cereal of temperate parts of the world, and is grown
extensively in both northern and southern hemispheres, whereas the
durum wheat is grown extensively in the Mediterranean region and in the
warmer, drier parts of Asia, North and South America.Rye can be
grown in colder parts of the world and is an important crop in central
Europe and Russia. Maize, which originated from the New World, is
now grown extensively throughout the tropics and subtropical regions of
both northern and southern hemispheres. Similarly, although rice was
originally of Asian origin, it is also grown in many parts of the world.
Although sorghum and some of the millets are not very important in
terms of world tonnage, they are especially well adapted to growing in
warm, dry climates and may be locally the most important cereals in such
regions as those bordering the southern edge of the Sahara desert.
The microbiology of cereals, during growth, harvest and storage is
dominated by the moulds and it is convenient to consider two groups of
fungi. The field fungi are well adapted to the sometimes rapidly changing
conditions on the surfaces of senescing plant material in the field.
Although they require relatively high water activities for optimum
growth, genera such asCladosporium, AlternariaandEpicoccumare able
to survive the rapid changes that can occur from the desiccation of a hot
sunny day to the cool damp conditions of the night. The genusFusarium
includes species which have both pathogenic and saprophytic activities.
Table 5.9 Some of the more important cereal crops
Botanical name Common name
Triticum aestivum Common wheat (bread wheat)
Triticum durum Durum wheat (pasta wheat)
Hordeumspp. Barley
Avena sativa Oats
Secale cereale Rye
Zea mays Maize (American corn)
Oryza sativa Rice
Sorghum vulgare Sorghum
Panicum miliaceum Millet
Pennisetum typhoideum Bulrush milletChapter 5 147