Introduction to Wheat
Wheat, a plant of the grass family, and the most widely cultivated food crop in the world. It may be grown in a variety of soils and climates, and its excellent storing and shipping qualities make it available to people almost everywhere. Wheat takes second place as a grain food only in eastern Asia, where rice is the leading cereal.
Wheat is ground into flour, which is used in making breads, crackers, noodles, and pastries. Wheat is also used in baby foods, sauces, soups, and candies. Bulgur, a type of cracked wheat that is first parboiled and dried, is prepared and eaten like rice. Wheat is also used in the production of beer, whiskey, starches, industrial alcohols, and some kinds of paper and cardboard. Another important use is as a livestock feed.
One of the earliest crops grown, wheat became a foundation for the great civilizations that grew up in Asia and Egypt thousands of years ago. Wheat is now the most important grain in international commerce.
The Wheat Plant
Wheat is an annual grass, and is found in wild as well as cultivated forms. The wild varieties, however, have no economic value. The cultivated plant is green when young, turning to golden-yellow as it matures. Several jointed stalks develop from each seed and grow to a height of two to six feet (60 cm to 1.8 m). Long, slender leaves grow from each joint, or node.Wheat is a green grass when young, maturing to golden-yellow.
Each stalk ends in a head, or spike, made up of a number of spikelets. The spikelets bear from one to five flowers, which develop into kernels. Wheat spikes are from two to eight inches (5 to 20 cm) long and bear from 20 to 50 kernels. Each kernel is protected by a pair of scalelike leaves, called glumes. Some varieties of wheat are called bearded because they have long bristles growing on the glumes.Wheat stalks end in a spike made up of a number of spikelets.
The kernel is made up of (1) several layers of bran, forming a tough outer coat; (2) the aleurone layer, rich in proteins and minerals; (3) the endosperm, mostly starch, but also containing proteins; and (4) the embryo, or germ, the part that develops into a new plant. The proteins in the endosperm are gliadin and glutenin. They interact to produce gluten, the substance that helps dough to rise, giving bread a light, fine texture. Bran, a good source of B vitamins and fiber, is used in breakfast cereals and in baked goods. Wheat germ is a rich source of vitamin E, and of the B-complex vitamins niacin and riboflavin. Because it does not keep well, and would add color, the wheat germ is usually taken out when wheat is milled for flour or breakfast cereal. It is eaten as a topping on yogurt or breakfast cereal, and in baked goods.
Kinds of Wheat
There are about 30 species of wheat, divided into more than 30,000 varieties. Plant breeders create new varieties by hybridization (crossbreeding between two varieties of the same species). The hybrid's parents are chosen for desirable qualities such as milling quality or resistance to cold or disease.
The most common species of cultivated wheat include:
(Triticum compactum), a dwarf species with short spikes, small kernels, and a low gluten content. It is used for making pastry flour. Club wheat will grow in poor soil. It is cultivated mainly in the western United States and Canada and in mountainous areas of Europe.Club wheat is a dwarf species with a low gluten content.
(T. aestivum), the leading commercial species, cultivated in temperate and subtropical areas around the world. It has a high gluten content. There are hundreds of varietiessome bearded, others beardless; some hard-kerneled, others soft-kerneled. Common wheat is used for making bread, pastries, breakfast cereals, alcoholic drinks, and many other products. Some varieties are used for livestock feed.
(T. durum), a bearded, drought-resistant species with hard kernels and a high gluten content. It is used chiefly for making pasta. Durum is grown in many parts of the world.
(T. monococcum), a hardy, bearded species. It produces one kernel to each spikelet. Einkorn was the first cultivated wheat and is the ancestor of most species of wheat grown today. It will grow in poor soil. Einkorn is grown mainly in the mountains of southern Europe as livestock feed.
(T. dicoccum), a bearded species cultivated mainly in Europe and Asia as livestock feed and a source of pastry flour.
(T. persicum), a species cultivated in the Caucasus.
(T. polonicum), a bearded species used for making bread. It is grown in parts of Europe and in northern Africa.
(T. turgidum), a species used mainly for making pastries and pasta. It is also used for livestock feed. It is grown in many parts of the world.
(T. sphaerococcum), a drought-resistant dwarf species grown in India.
(T. spelta), a species grown mainly in Germany and northern Spain to make pastries. It is also used for livestock feed.
Some wheat-growing countries have set up rigid official government standards for wheat. The U.S. Department of Agriculture recognizes 7 commercial classes and 15 subclasses. These groups are net directly related to botanical classifications, but are based on the color, texture, size, and shape of the kernel. The seven classes are: hard red spring; hard red winter; soft red winter; amber durum; red durum; white; and mixed. Each class is grown in particular regions of the United States. The Department of Agriculture recognizes six wheat growing regions. These regions are shown in the map below, along with the major class (or classes) of wheat grown in them. In Canada, the classes of wheat grown are the same as those grown in the United States.
How Wheat Is Raised
Wheat has a wide range of cultivation because of its many varieties. Some kinds of wheat are grown at elevations of 12,000 feet (3,700 m), others below sea level. Wheat is grown in the tropics and within the Arctic Circle. However, the most valuable wheat can be grown successfully only in the temperate regions where the annual rainfall is less than 30 inches (760 mm). The soils best suited for the growing of wheat are loamy and rich.
Wheat farmers usually practice crop rotation, to keep form exhausting the soil and to control the weeds, plant diseases, and insect pests. In some areas, wheat land is allowed to remain idle, or fallow, a year or two to conserve moisture and minerals.
In the larger wheat-producing countries, wheat farming is highly mechanized. In developing countries, however, the work is generally still done by hand, or with the help of simple machines.
After the ground is prepared by plowing and certain other methods, machines plant the seeds (kernels) either by sowing them broadcast (that is, distributing them on the surface of the ground) or by drilling furrows and planting the seeds in rows. Spring wheats are planted as early as the soil can be worked; winter wheats are planted in early fall. The leaves of spring wheat appear above ground about two weeks after planting. Winter wheat sprouts, stops growing with the first freeze, then resumes its growth in the spring.
Wheat requires little cultivation except weed control. Weeds are killed by plowing between the rows of drill-planted wheat, or by spraying with chemicals.
To prevent scattering of the kernels, wheat is usually harvested before it is fully ripe. There are several steps in harvesting: cutting, or reaping, the stalks; threshing and winnowing, to separate the kernels from the spikes, glumes, and other chaff; sifting and sorting the grain; loading the grain into trucks; and binding the straw. On large farms, huge machines called combines, manned by small crews, perform all of the harvesting processes. .)
Wheat must be stored in dry, well-ventilated buildings that keep out insect pests. Wheat is stored for a short time in bins or granaries on the farms. It is then hauled to country elevators, tall structures where the grain is dried and stored until it is sold locally or shipped to terminal elevators. Terminal elevators are immense buildings, each holding 1,000,000 bushels (27,000 metric tons) or more. They are grouped at large inland distributing centers and at seaports, where the wheat may be stored almost indefinitely. .)
Diseases and Insect Pests
Serious diseases of wheat caused by fungi include stem and leaf rust, smut, scab, seedling blight; and root rot. Less widespread damage is caused by bacteria and viruses. Wheat diseases may be controlled to some extent with fungicides and germicides. The best method of control is the use of disease-resistant hybrids. Developing such hybrids is a never-ending task, however, because many disease-producing organisms are able to mutate into forms that can feed on the new strains of wheat.
The Hessian fly is wheat's worst insect enemy. It usually attacks winter wheat, which may be protected by planting after the fly's hatching time is past. Other pests are chinch bugs, aphids, cutworms, mites, and grasshoppers. These pests may be controlled by crop rotation, sprays, and proper soil preparation. Stored grain may be attacked by meal worms.
Wheat Production and Marketing
Wheat is grown chiefly in two wide belts: between 30 and 55 North latitude, and between 30 and 40 South latitude. China, the United States, India, and Russia lead in world wheat production.
Kansas and North Dakota are the leading wheat-producing states. Canada's great wheat belt includes Saskatchewan, Alberta, and Manitoba.
The individual farmer usually sells grain to the owners of country elevators. (Sometimes the elevators are owned cooperatively by a number of farmers in the area.) The wheat may then be sold to local processors, or shipped to terminal elevators. Terminal markets weigh and inspect the grain, and help the owners of the wheat sell it. Wheat is often held for long periods in terminal elevators even after it is sold, because many buyers arrange for future delivery dates.
Most wheat is bought and sold at large grain (or commodity) exchanges such as the Chicago Board of Trade. Because of grading standards, it is not necessary for buyers to see samples, although samples may be available.
Except during a major war, most wheat-exporting countries tend to accumulate large surpluses of the grain. These surpluses lead to low prices and threaten wheat growers with financial ruin. Governments have tried various methods of solving this problem.
In the United States, the federal government has imposed price supports, paid wheat farmers for limiting crops, and made loans on stored grain. However, these methods have been attacked as contributing to overproduction instead of lessening it. The United States government also conducts research to find new uses for wheat, and promotes the use of surplus wheat to feed needy peoples of the world. On an international scale, various pacts have been signed to help stabilize the wheat market.
Wheat undoubtedly developed from the accidental crossbreeding of certain grasses and by mutation (a spontaneous change by which the offspring differs from the parents). It was cultivated long before the beginning of written history. Archeologists have found evidence that wheat was grown by Stone Age people in western Asia Minor at least 10,000 years ago. Bread wheat was grown in the same locality and in the Nile Valley as early as 4,000 years ago.
Wheat was brought to the Western Hemisphere early in the 16th century. It was cultivated by American colonists on the Atlantic coast in the 17th century, but was not as well adapted to this region as was corn. Pioneers moving west took wheat with them.
began in the United States in the 19th century. In 1830, Cyrus McCormick invented a reaping machine that helped revolutionize the wheat industry. Threshing and binding machines were also invented during the 19th century. Improved transportationnotably railways and steamshipsgreatly broadened the market for wheat from the central United States and Canada. New varieties of wheat from other countries helped to expand the wheat belts of the Western Hemisphere.
Mechanization of the wheat industry continued in the 1900's as the combine became the major harvesting and threshing equipment. Hybrids were developed that could resist drought, cold, and disease, and that had superior milling and baking qualities.
Until 1914, the world wheat market remained fairly steady. During the war, wheat production in exporting countries was expanded. After the war, European nations began more extensive wheat farming, leaving traditional exporting countries with surpluses. This cycle was repeated with World War II.
In the decades after the war, the largest wheat-exporting nations were the United States, Canada, Australia, and Argentina. They sold to major markets such as Western Europe, China and Japan, and India and Pakistan. Russia was once an exporter of wheat, but the country became a major importer in the 1960's, when its agricultural system proved incapable of supporting a growing population. France, which formerly produced only enough to meet its own needs, joined the ranks of the exporting nations.
In the early 1960's, new hybrids of high-yield wheat were developed in Mexico. Their introduction into other parts of the world made some nations self-sufficient wheat producers and other nations less dependent on imports. In the early 1990's, scientists succeeded for the first time in using techniques of genetic engineering to produce desirable characteristics in wheat.