Wheat is a cereal grain that originated in the Levant and the Ethiopian Highlands, but is now cultivated worldwide. The most common forms of wheat are white and red wheat. However, other natural forms of wheat exist. Purple wheat, a species that is rich in anti-oxidants, grows in the highlands of Ethiopia. Other commercially minor but nutritionally-promising species of naturally evolved wheat include black, yellow and blue wheat.
Wheat is grown on more than 240 million hectares, larger than for any other crop – with 200 million hectares in the developing world. World production of wheat is almost 700 million tons, making it the third most-produced cereal after maize (well over 800 million tonnes) and rice (over 700 million tons).
The world’s top producers are China, India, Russia and the United States in that order – these four nations producing almost half of the total world production. China's share is almost one-sixth of the world production.
Together with rice, wheat is the world's most favored staple food. In terms of total production tonnages used for food, it is currently second to rice as the main human food crop and ahead of maize, after allowing for maize's more extensive use in animal feeds. Wheat provides more nourishment for humans than any other food source. It is a major diet component for populkations and cultures widely dispersed throughout the world because of the wheat plant’s agronomic adaptability, with the ability to grow from frigid near-arctic regions to torrid equatorial countries; from hot and humid sea level holdings to the plains of Tibet at 4000 meters above sea level.
Wheat also offers ease of grain storage and ready conversion of grain into flour for making a wide variety of highly edible, delicious, interesting and satisfying foods. The grain is used to make flour for leavened, flat and steamed breads, biscuits, cookies, cakes, breakfast cereal, pasta, noodles, and couscous. Most breads are made with wheat flour, including many breads named for the other grains they contain – like rye and oat breads. It is also fermented to make beer and other alcoholic beverages.
Whole wheat grain can be milled to leave just the endosperm for white flour. The by-products of this are bran and germ. The whole grain is a concentrated source of vitamins, minerals, and protein, while the refined grain is mostly starch. Wheat is the most important source of carbohydrate in a majority of countries, and is the primary food staple in North Africa and the Middle East, with growing popularity in Asia. In the Central and West Asia and North Africa (CWANA) region, per capita annual human wheat consumption is the highest in the world.
Globally, wheat is the leading source of vegetable protein in human food, having a higher protein content than either maize or rice, the other major cereals. Wheat protein is easily digested by nearly 99% of human population, the exception being the 1% with gluten sensitivity. Wheat also contains a diversity of minerals, vitamins and fats (lipids).
Wheat is also planted to a limited extent as a forage crop for livestock, and its straw can be used as a construction material for roofing thatch. It is also increasingly being fermented for biofuel.
The crop is widely cultivated as a cash crop because it produces a good yield per unit area, grows well in a temperate climate even with a moderately short growing season, and yields a versatile, high-quality flour that is widely used in baking - the popularity of foods made from wheat flour creates a large demand for the grain, even in economies with significant food surpluses. World trade in wheat is greater than for all other crops combined.
Half of rain-fed farming systems growing wheat in developing countries suffer from poor or erratic rainfall, poor soils, aggressive diseases, low-yielding varieties and sometimes extreme heat and/or cold. In some of the areas, this is compounded by isolation due to geographical factors and/or poor infrastructure, and limited investment in research.
These systems cover large areas of Asia, northern, southern, and eastern Africa, and Latin America, and include countries where over half of the daily food requirement is met by wheat alone, yet their overall productivity is lower than all other geographic regions of the world, and lower than the world average. Some of these areas experience widespread and serious micronutrient malnutrition.
Irrigated/Intensive high-productivity wheat-growing agricultural systems found in Asia, North Africa, and Latin America also face serious problems, including the unsustainable exploitation of water and soils, inefficient use of chemical inputs, and emerging or worsening disease and pest problems.
China and India being respectively the world’s largest and second largest producers of wheat and also the world’s two most populous nations, Chinese and Indian wheat production are of critical importance to global food security.
Climate change and changing water use patterns are projected to reduce the amount of water available for irrigated wheat production in both countries. It is therefore vitally important that more water-use-efficient farming systems and wheat cultivars are identified.