cereal plant of the genus Triticum of the family Gramineae (grass family), a major food and an important commodity on the world grain market.
The wheat plant is an annual, probably derived from a perennial; the ancestry of and precise distinctions between species are no longer always clear. For its early growth wheat thrives best in cool weather. Among the more ancient, and now less frequently cultivated, species are einkorn (T. monococcum), emmer (T. dicoccum), and spelt (T. spelta). Modern wheat varieties are usually classified as winter wheats (fall-planted and unusually winter hardy for grain crops) and spring wheats. Approximately three fourths of the wheat grown in the United States is winter wheat.
Flour from hard wheats (varieties evolved for the most part from T. aestivum) contains a high percentage of gluten and is used to make bread and fine cakes. The hardest-kerneled wheat is durum (T. durum); its flour is primarily used in the manufacture of macaroni, spaghetti, and other pasta products. White- and soft-wheat varieties are paler and have starchy kernels; their flour is preferred for piecrust, biscuits, and breakfast foods. Wheat is used in the manufacture of whiskey and beer, and the grain, the bran (the residue from milling), and the vegetative plant parts make valuable livestock feed. Before the introduction of corn into Europe, wheat was the principal source of starch for sizing paper and cloth.
Wheat is susceptible to many pests and diseases, the more destructive including rust, bunt (see smut), and the Hessian fly and chinch bug. All wheat-producing countries carry on breeding experiments to improve existing varieties or to obtain new ones with such dominant characteristics as disease resistance, increased hardiness under specific environments, and greater yield.
The great wheat-producing countries of the world are the United States, China, and Russia; extensive wheat growing is carried on also in India, W Europe, Canada, Argentina, and Australia. In the United States the wheat belt covers the Ohio Valley, the prairie states, and E Oregon and Washington; Kansas leads the states in production. Large-scale mechanized farming and continued planting of wheat without regard to crop rotation have exhausted the soil of large areas. High-yield wheat, one of the grains resulting from the Green Revolution, requires optimal growth conditions, e.g., adequate irrigation and high concentrations of fertilizer.
Wheat was one of the first of the grains domesticated by humans (see grain). Its cultivation began in the Neolithic period; some ancient species of wheat were domesticated around 10,000 years ago in what is now Turkey. A millennium later wheat had spread to the Near East, and it was cultivated in Egypt by 5000 B.C. By way of Iran, wheat reached India around 4000 B.C. and China around 2000 B.C. About 8,000 years ago it arrived in Greece from Turkey, and then spread throughout Europe, reaching Britain around 3000 B.C. The civilizations of W Asia and of the European peoples have been largely based on wheat, while rice has been more important in E Asia. Since agriculture began, wheat has been the chief source of bread for Europe and the Middle East. It was introduced into Mexico by the Spaniards c.1520 and into Virginia by English colonists early in the 17th cent.
Wheat is classified in the division Magnoliophyta, class Liliopsida, order Cyperales, family Poaceae (Gramineae).
- See publications issued by the U.S. Dept. of Agriculture; The Book of Wheat (1908, repr. 1973). ,
- Evans, L. T.;Peacock, W. J., ed. Wheat Science: Today and Tomorrow (1981).
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