Grain

Cereals, grains or cereal grains, are grasses (members of the monocot families Poaceae or Gramineae) cultivated for the edible components of their fruit seeds (botanically, a type of fruit called a caryopsis) - the endocarp, germ and bran. Cereal grains are grown in greater quantities and provide more food energy worldwide than any other type of crop; they are therefore staple crops. In their natural form (as in whole grain), they are a rich source of vitamins, minerals, carbohydrates, fats and oils, and protein. However, when refined by the removal of the bran and germ, the remaining endocarp is mostly carbohydrate and lacks the majority of the other nutrients. In some developing nations, grain in the form of rice, wheat, or maize (in American terminology, corn) constitutes a majority of daily sustenance. In developed nations, cereal consumption is more moderate and varied but still substantial.

The word cereal derives from Ceres, the name of the Roman goddess of harvest and agriculture.

Production

The following table shows annual production of cereal grains, in 1961, 2005 and 2006, ranked by 2006 production. All but buckwheat and quinoa are true grasses (these two are pseudocereals).

Maize, wheat and rice, between them, accounted for 87% of all grain production, worldwide, and 43% of all food calories in 2003. Other grains that are important in some places, but that have little production globally (and are not included in FAO statistics), include:

• Teff, popular in Ethiopia but scarcely known elsewhere. This ancient grain is a staple in Ethiopia. It is high in fiber and protein. Its flour is often used to make injera. It can also be eaten as a warm breakfast cereal similar to farina with a chocolate or nutty flavor. Its flour and whole grain products can usually be found in natural foods stores.
• Wild rice, grown in small amounts in North America
• Amaranth, ancient pseudocereal, formerly a staple crop of the Aztec Empire (besides maize)
• Kañiwa, close relative of quinoa

Several other species of wheat have also been domesticated, some very early in the history of agriculture:

• Spelt, a close relative of common wheat
• Einkorn, a wheat species with a single grain
• Emmer, one of the first crops domesticated in the Fertile Crescent
• Durum, the only tetraploid species of wheat currently cultivated, used to make semolina

Farming

While each individual species has its own peculiarities, the cultivation of all cereal crops is similar. All are annual plants; consequently one planting yields one harvest. Wheat, rye, triticale, oats, barley, and spelt are the cool-season cereals. These are hardy plants that grow well in moderate weather and cease to grow in hot weather (approximately 30°C but this varies by species and variety). The other warm-season cereals are tender and prefer hot weather.

Barley and rye are the hardiest cereals, able to overwinter in the subarctic and Siberia. Many cool-season cereals are grown in the tropics. However, some are only grown in cooler highlands, where it may be possible to grow multiple crops in a year.

Planting

The warm-season cereals are grown in tropical lowlands year-round and in temperate climates during the frost-free season. Rice is commonly grown in flooded fields, though some strains are grown on dry land. Other warm climate cereals, such as sorghum, are adapted to arid conditions.

Cool-season cereals are well-adapted to temperate climates. Most varieties of a particular species are either winter or spring types. Winter varieties are sown in the autumn, germinate and grow vegetatively, then become dormant during winter. They resume growing in the springtime and mature in late spring or early summer. This cultivation system makes optimal use of water and frees the land for another crop early in the growing season. Winter varieties do not flower until springtime because they require vernalization: exposure to low temperature for a genetically determined length of time. Where winters are too warm for vernalization or exceed the hardiness of the crop (which varies by species and variety), farmers grow spring varieties. Spring cereals are planted in early springtime and mature later that same summer, without vernalization. Spring cereals typically require more irrigation and yield less than winter cereals.

Period

Once the cereal plants have grown their seeds, they have completed their life cycle. The plants die and become brown and dry. As soon as the parent plants and their seed kernels are reasonably dry, harvest can begin.

In developed countries, cereal crops are universally machine-harvested, typically using a combine harvester, which cuts, threshes, and winnows the grain during a single pass across the field. In developing countries, a variety of harvesting methods are in use, from combines to hand tools such as the scythe or cradle.

If a crop is harvested during wet weather, the grain may not dry adequately in the field to prevent spoilage during its storage. In this case, the grain is sent to a dehydrating facility, where artificial heat dries it.

In North America, farmers commonly deliver their newly harvested grain to a grain elevator, a large storage facility that consolidates the crops of many farmers. The farmer may sell the grain at the time of delivery or maintain ownership of a share of grain in the pool for later sale. Storage facilities should be protected from small grain pests, rodents and birds.

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