Wheat

Nomenclature

Traditionally there are three major cultivated species of wheat: Triticum aestivum, Common Wheat, used to make bread, T. durum, Durum, used to make pasta, and T. compactum, Dwarf Wheat, used to make cakes, crackers, and pastries. However, there are now more than 25,000 cultivars that are the result of complex interbreeding that makes wheat nomenclature extremely complex. Since there are various classifications you might find that the same kind of wheat has been given different names depending on your source of information. Thousands of agricultural cultivars (domesticated variants) have arisen based on different desired characteristics: growing season (e.g. winter wheat, spring wheat); protein content (soft wheat, hard wheat); quality of the protein gluten (the strength and elasticity that affects formation of dough and rolling); and colour (red, white, or amber). Red-brown colouring is due to astringent phenolic compounds so white wheats have fewer phenols and are therefore more mild in flavour. The yellow colouration of durum wheat and semolina flour derives from the carotenoid pigment lutein.

Selection and breeding of wheat has been so intensive under cultivation that the most practical way of listing the different kinds is under Group names (formal clasification categories adopted by the International Code of Nomenclature for Cultivated Plants) based on familiar common names and breeding types, rather than under their botanical names – although this still does not remove potential confusion as the genus undergoes constant revision. Those growing wheat communicate about it simple terms knowing what their genberal uses are say, ‘Hard White’ (hard, pale, chalky grains with moderate protein suited to dryer temperate regions: popular for bread and brewing) or ‘Soft White’ (soft, pale, low protein wheat suited to wetter temperate regions. Used for pies and pastries)

Hexaploids^[1]

Aestivum Group (T. aestivum) – Common Wheat, Bread Wheat – the most widely cultivated of all the wheats
Spelta Group (T. spelta) – a close relative of Common Wheat

Tetraploids

Durum Group (T. durum) – the second most widely cultivated wheat
Dicoccon Group (T. dicoccon) also known as Emmer, – widely cultivated in ancient times
Turgidum Group (T. turgidum ) – T. turanicum) is known as Khorasan – an ancient grain from Khorasan, a historical region of today’s Afghanistan and northeastern Iran. High yielding with a rich flavour

Diploids

Einkorn (T. monococcum) – domesticated at about the same time as Emmer and with many later variants
Durum Group – a diploid variant of tetraploid durum with a hard, translucent, pale grain used to make semolina flour for pasta; high in protein especially gluten
Aestivum Group – includes the winter and spring wheats like ‘Hard Red Spring’ (hard, brown, high-protein gluten suited for bread and hard baked products); ‘Hard Red Winter’ (hard, brown, mellow high-protein used for bread and hard baked products. Added to other flours to increase protein in pastry flour for pie crusts); ‘Soft Red Winter’ (low-protein used for cakes, pastries, pie crusts, biscuits, and muffins, and some self-raising flours)

Etymology

The word ‘wheat’ derives from the Old English meaning white, which distinguish grains of wheat from the darker grains of barley and rye.

Botany

About 20 species of annual species native to the Mediterranean and SW Asia, a number of these being cultigens (altered by humans) whose ancestry is still being unravelled. Wheat is in the botanical genus Triticum which is in the grass family Poaceae. Plants grow to 1 m or so, with mostly hollow stems. The flowering heads or spikelets consist of 20-100 flowers arranged in groups of 2-6. The grain kernel is a type of fruit called a caryopsis. In domesticated wheat, grains are larger, and remain attached to the ear during harvesting although in the wild ancestors they break up. The characteristic of attached grains might not have been intended but it hada selective advantage since it made seed gathering easier. However, as a consequence, domesticated strains of wheat cannot survive in the wild.

Origin & globalization

Wheat is the paradigm domesticated plant illustrating the coevolution of human and plant especially in the major phase of human cultural evolution when widespread agriculture created lactose tolerance that is not found, for example, in Australian Aboriginals.

Wheat was probably the world’s first large-scale plant domestication – the first major genetic alteration by human selection. It has subsequently followed human history in tracing a path of plant globalization linked to human environmental, social, and economic history through population, transport and communication including human migration, social organization, and technological development.

Emma, Einkorn, & Bread Wheat

Etymology: German Emmer, variant of Amelkorn, from amel – starch and Latin amylum: first use: 1908. German Einkorn or single grain

Chemistry

Wheat is an important source of carbohydrates while the vegetal protein makes up about 13%, quite high compared to other major cereals, but relatively poor in the supply of essential amino acids. However, whole grain wheat is a valuable source of nutrients and dietary fiber. Thiamin, riboflavin, niacin, and small amounts of vitamin A are present but milling removes most of these along with the bran and germ. The protein gluten makes dough elastic and pliable so that it can be used for many foods: including breads, noodles, and pasta. A few people are susceptible to gluten-induced coeliac disease, non-coeliac gluten sensitivity, gluten ataxia and dermatitis herpetiformis. The nutritional value can vary with climate and soil. The grains do contain some compounds that are detrimentl to health such as those that interfere with iron absorption so the bones of people raised on a diet mainly of wheat show symptoms of iron deficiency and archaeological records also indicate ricketts (vitamin D deficiency). The association of dairy products with agriculture is indicated by a lactose-tolerance that arose about 8000 years ago t ospread rapidly through European populations.

Breeding

Global production & export

Wheat can be cultivated in a range of soils and over much of the world at altitudes from sea level to over 3000 m. Annual rainfall of 254 mm is generally considered the minimum.

In 2016, global wheat production was 749 million tonnes. Wheat is the primary food staple in North Africa and the Middle East, and is used increasingly in Asia. Unlike rice, wheat production is more widespread globally, though 47% of the world total in 2014 was produced by just four countries – China, India, Russia and the United States.

The most popular varieties are white and red wheat but there are also black, yellow and blue cultivars.

Wheat futures contracts are traded on the Chicago Board of Trade, Kansas City Board of Trade, and Minneapolis Grain Exchange,

In the 20th century, global wheat output expanded by about 5-fold, but until about 1955 most of this reflected increases in wheat crop area, with lesser (about 20%) increases in crop yields per unit area. After 1955 however, there was a ten-fold increase in the rate of wheat yield improvement per year, and this became the major factor allowing global wheat production to increase. Thus technological innovation and scientific crop management with synthetic nitrogen fertilizer, irrigation and wheat breeding were the main drivers of wheat output growth in the second half of the century. There were some significant decreases in wheat crop area, for instance in North America.[82] Better seed storage and germination ability (and hence a smaller requirement to retain harvested crop for next year’s seed) is another 20th century technological innovation. In Medieval England, farmers saved one-quarter of their wheat harvest as seed for the next crop, leaving only three-quarters for food and feed consumption. By 1999, the global average seed use of wheat was about 6% of output. Several factors are currently slowing the rate of global expansion of wheat production: population growth rates are falling while wheat yields continue to rise, and the better economic profitability of other crops such as soybeans and maize, linked with investment in modern genetic technologies, has promoted shifts to other crops.

Map of world wheat production c. 2003
Courtesy Wikimedia Commons – AndrewMT Accessed 11 July 2017

Exporters in 2013: United States (33.2 million tonnes), Canada (19.8 million tonnes), France (19.6 million tonnes), Australia (18 million tonnes), and the Russian Federation (13.8 million tonnes).[86] The largest importers of wheat in 2013 were, in order of imported quantities: Egypt (10.3 million tonnes), Brazil (7.3 million tonnes), Indonesia (6.7 million tonnes), Algeria (6.3 million tonnes) and Japan (6.2 million tonnes).[86]In the rapidly developing countries of Asia and Africa, westernization of diets associated with increasing prosperity is leading to growth in per capita demand for wheat at the expense of the other food staples.[6][8](Wheat is produced in almost every state in the United States, and is the principal cereal grain grown in the country.[1] The type and quantity vary between regions. The United States is ranked third in production volume of wheat, with almost 58 million tons produced in the 2012–2013 growing season, behind only China and India. (But the combined production of all European Union nations is larger than that of China.[2]) The United States ranks first in crop export volume; almost 50% of its total wheat production is exported.)

In the past, there has been significant governmental intervention in wheat markets, such as price supports in the US and farm payments in the EU. In the EU, these subsidies have encouraged heavy use of fertilizer inputs with resulting high crop yields. In Australia and Argentina, direct government subsidies are much lower.

Geographic distribution of wheat production in USA
Acres by County
Courtesy Wikimedia Commons – USIA Accessed 11 July 2017

Wheat is a temperate crop growing in regions with rainfall of 30-90 cm (12 and 36 inches). Wheat is grown as a winter or spring crop with the severity of the winter determining which is preferred. Winter wheat is sown in autumn, spring wheat in spring or sometimes in autumn when winters are mild. Barley and rye can be grown in soil less fertile than that required for wheat.

Wheat normally needs between 110 and 130 days between sowing and harvest, depending upon climate, seed type, and soil conditions (winter wheat lies dormant during a winter freeze). Optimal crop management requires that the farmer have a detailed understanding of each stage of development in the growing plants. In particular, spring fertilizers, herbicides, fungicides, and growth regulators are typically applied only at specific stages of plant development.

Agricultural cultivation using horse collar leveraged plows (at about 3000 BCE) was one of the first innovations that increased productivity. Much later, when the use of seed drills replaced broadcasting sowing of seed in the 18th century, another great increase in productivity occurred. Agricultural cultivation using horse collar leveraged plows (three thousand years ago) increased cereal grain productivity yields, as did the use of seed drills which replaced broadcasting sowing of seed in the eighteenth century.

Yields of pure wheat per unit area increased as methods of crop rotation were applied to long cultivated land, and the use of fertilizers became widespread. Improved agricultural husbandry has more recently included threshing machines and reaping machines (the ‘combine harvester’), tractor-drawn cultivators and planters, and better varieties (see Green Revolution and Norin 10 wheat). Great expansion of wheat production occurred as new arable land was farmed in the Americas and Australia in the 19th and 20th centuries.

Processing

The four wild species of wheat, along with the domesticated einkorn, emmer, and spelt have hulls or husks (botanically these are enclosing glumes) and (in domesticated wheats) a semi-brittle rachis (the axis holding the grains) that breaks when threshed so that the wheat ear breaks up into spikelets. To isolate the grains from the husks and chaff further milling or pounding is needed. Durum wheat and common wheat do not have these hulls. Hulled wheats are often stored as spikelets as the hulls are protection against pests.

Grain is cleaned and then conditioned by the addition of water so that the kernel breaks up properly. In milling, the grain is cracked and then passed through a series of rollers. As the smaller particles are sifted out, the coarser particles pass to other rollers for further reduction. About 72 percent of the milled grain is recovered as white flour. Flour made from the whole kernel is called graham flour and becomes rancid with prolonged storage because of the germ-oil content retained. White flour, which does not contain the germ, preserves longer. Inferior and surplus wheats and various milling by-products are used for livestock feeds.

The greatest portion of the wheat flour produced is used for breadmaking. Wheats grown in dry climates are generally hard types, having protein content of 11–15 percent and strong gluten (elastic protein). The hard type produces flour best suited for breadmaking. The wheats of humid areas are softer, with protein content of about 8–10 percent and weak gluten. The softer type of wheat produces flour suitable for cakes, crackers, cookies, and pastries and household flours. Durum wheat semolina (from the endosperm) is used for making pastas, or alimentary pastes.

Consumed worldwide by billions of people, wheat is a significant food for human nutrition, particularly in the least developed countries where wheat products are primary foods.[1][9] When eaten as the whole grain, wheat is a healthy food source of multiple nutrients and dietary fiber recommended for children and adults, in several daily servings containing a variety of foods that meet whole grain-rich criteria.[9][55][67][68] Dietary fiber may also help people feel full and therefore help with a healthy weight.[69] Further, wheat is a major source for natural and biofortified nutrient supplementation, including dietary fiber, protein and dietary minerals.[70]

In genetically susceptible people, gluten – a major part of wheat protein – can trigger coeliac disease.[54][74] Coeliac disease affects about 1% of the general population in developed countries.[75][74] There is evidence that most cases remain undiagnosed and untreated.[74] The only known effective treatment is a strict lifelong gluten-free diet.[74]While coeliac disease is caused by a reaction to wheat proteins, it is not the same as a wheat allergy.[75][74] Other diseases triggered by eating gluten are non-coeliac gluten sensitivity,[75][14] (estimated to affect 0.5% to 13% of the general population),[76] gluten ataxia and dermatitis herpetiformis.[14]

Commercial Use

Wheat provides humans with more than bread. It is used for fermentation to make biofuel, beer, and vodka; it is planted as a forage crop for livestock and the straw can be used as fodder for livestock or as a construction material for roofing thatch (A. Smith 1995). In the British Isles, wheat straw (thatch) was used for roofing in the Bronze Age, and was in common use until the late 19th century.[25]

Raw wheat can be ground into flour or, using hard durum wheat only, can be ground into semolina; germinated and dried it produces malt; crushed or cut it makes cracked wheat; parboiled (or steamed), dried, crushed and de-branned into bulgur also known as groats. If the raw wheat is broken into parts at the mill, as is usually done, the outer husk or bran can be used several ways. Wheat is a major ingredient in such foods as bread, porridge, crackers, biscuits, Muesli, pancakes, pies, pastries, cakes, cookies, muffins, rolls, doughnuts, gravy, beer, vodka, boza (a fermented beverage), and breakfast cereals.

Harvested wheat grain that enters trade is classified according to grain properties for the purposes of the commodity markets. Wheat buyers use these to decide which wheat to buy, as each class has special uses, and producers use them to decide which classes of wheat will be most profitable to cultivate.
Wheat 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. Most breads are made with wheat flour, including many breads named for the other grains they contain, for example, most rye and oat breads. The popularity of foods made from wheat flour creates a large demand for the grain, even in economies with significant food surpluses.

In recent years, low international wheat prices have often encouraged farmers in the United States to change to more profitable crops. In 1998, the price at harvest of a 60 pounds (27 kg) bushel[79] was $2.68 per.[80] Some information providers, following CBOT practice, quote the wheat market in per ton denomination.[81] A USDA report revealed that in 1998, average operating costs were $1.43 per bushel and total costs were $3.97 per bushel.[80] In that study, farm wheat yields averaged 41.7 bushels per acre (2.2435 metric ton/hectare), and typical total wheat production value was $31,900 per farm, with total farm production value (including other crops) of $173,681 per farm, plus $17,402 in government payments. There were significant profitability differences between low- and high-cost farms, mainly due to crop yield differences, location, and farm size.

Australia^[50]

Wheat is Australia’s most important and valuable agricultural commodity. In 2003-04 about 30,000 farmers in Australia grew wheat on nearly half of the agricultural land used for crops, production valued at $5.6 billion or 15% of the total value of farm production. Overseas sales were over $3.4 b and high on the world market.

The areas chosen for wheat farming are determined by soil type and fertility, topography, and rainfall. Rain should predominantly fall during the winter and spring months, essentially at least 400 and 600 mm pa, equivalent to an area west of the Great Dividing Range known as the wheat belt which stretches from Central Queensland through New South Wales and Victoria and on to South Australia in the form of a narrow crescent, continuing into the south west of Western Australia including a small area of Tasmania. The area dedicated to wheat and with a roughly corresponding yield in 2003-2004 was NSW 3983, Vic 1409, Qld 790, SA 1960, WA 4917, Tas 8, Total 13,067 ‘000 ha.

Australian wheat farming districts – 2000-2001
Yields are shown in tonnes per sq km
From AgStats on GSP (7117.0.30.001) CD-ROM product 1996-97 to 2000-01

In the 20th century wheat yields gradually improved: in the early 1940s average yield reached 1 tonne per ha with the introduction of new varieties. In the 1950s 1.5 tonnes/ha was achieved, largely maintained to the present with the record national average yield of 2.11 tonnes/ha set in 2002.

Fluctuations in the price of wheat have been caused by wars, the Depression, unreliable climate, and volatile markets, the overall trend being down. Most wheat farms are family businesses owned by either a sole proprietor or a family and it is usually combined with raising sheep, beef cattle or growing other crops since continued growing of one crop type leads to deterioration of soils and increase in pests and diseases which are discouraged by crop rotation. Since the 1970s lupins and rape, canola, and field peas have been popular in crop rotation.

Planting usually occurs in April, May and June as the seed requires the colder weather to germinate and allows harvesting before the onset of harsh summer weather. In Queensland this is during September and October and it ends in Western Australia during January.

Australia grows mostly white-grained varieties with a high rate of flour extraction, not so much the red grained varieties popular in North America.

Most popular in Australia are Bread Wheat Triticum aestivum and Durum Triticum durum, the former a common milling wheat. Milled wheat used for bread and noodles requires a hard grain with a high level of protein for better volume, softer crumb and better keeping so Durum is only grown in northern NSW and eastern SA making up less than 3% of the total Australian wheat crop.

Australia consumes around 5 million tonnes of wheat annually, the rest being exported. About 2.5 million tonnes are used for flour, whole grain products, Beer etc., for human consumption, and in the production of gluten and starch etc., for industrial uses and a further 2.5 million tonnes used for stock feed. This sector is sensitive to price movements but is a rapidly growing market responding in 2003-2004 to an expanding livestock industry. About 500,000 tonnes p.a. is used for seed.

Historically Commonwealth and State governments provided the industry with financial assistance and regulatory control but this has varied as circumstances have changed.

Colonial agriculture

The European agricultural tradition arrived in Australia with (Governor Phillip) who, wanting to make the colony self-sufficient in food set aside nine acres of land at Farm Cove. Unsuccessful he the established a 40-acre government farm at Parramatta, and allowed ex-convicts to own their own farms, the first being James Ruse. In 1790, 200 bushels (approximately 5.4 tonnes) of wheat was harvested as seed for future crops and by 1799 Liberty Plains (now Sydney’s western suburbs Homebush and Strathfield) supported 6,000 acres of wheat. However, obstacles included the use of inappropriate wheat varieties, labour shortages, poor tools and agricultural knowledge, infertile soil, poor and irregular rainfall, and plant diseases.

Victoria, South Australia and Western Australia were settled in the 1830s and 1840s with whaet cultivation expanding rapidly in South Australia from eight hectares in 1838 to 7,592 hectares in 1844. Technological developments included the scrub roller, the ‘stump jump’ plough, and the header harvester facilitating the clearing and preparation of large tracts of land. The inland country railway network of the 1880s gave an enormous boost to the industry but there were also new wheat varieties including those resistant to disease and mechanical harvesting. William Farrer in the late 1800s, bred a number of new wheat varieties, notably the early-maturing ‘Federation’, which was drought and disease resistant.

Later developments included mixed farming, crop rotation, use of fertilizers, improved cultivation and, after 1940, the use of tractors, bulk grain handling systems, chemicals to combat pests, diseases, and weeds.

Global context

In 2003-04, 102 million tonnes of wheat were traded on the international market. The United States exported the most wheat, while Canada and Australia each sold about the same amount. The European Union, which includes the major wheat producing countries of France and Germany was, collectively, the biggest producer (106 million tonnes) but ranked only fourth as an exporter with 10 million tonnes. China, India and Russia are also major producers but are relatively minor players in the export business. While Australia produces only about 3% of the world’s wheat it exports to more than 40 countries. Australia’s total wheat exports represent around 15% of the annual world wheat trade.

Australia’s main wheat export markets are in Asia and the Middle East with Indonesia, Egypt, Iraq and Japan leading the importers over the past three years. In recent years the market for Australian wheat exports to China has grown strongly.

Breeding

Wheat breeding has produced cultivars suited to Australia’s dry environment including resistance to stem rust and leaf rust which both reached epidemic levels in the early 20th-century also white-grained, medium to high protein and water efficient cultivars. The latter have reduced water usage and improved yield by diverting water use from the foliage to ear production.

Trade with the UK ceased in the 1960s so alternative markets were sought in the Middle East and Asia, Australian hard white cultivars proving especially popular in East Asia where they are used in the production of instant and fresh noodles.

From the early 1970s to mid-1980s new, high yielding varieties became available to Australian growers leading to today’s breeding managed by the Grains Research and Development Corporation (GRDC).

Commentary

Cereals, and especially wheat, have been at the centre of human culture since the Agricultural Revolution, featuring in key cultural themes of industrialization, globalization, and sustainability as affected by changes in society, economics, and the environment. The excess energy made available by cereals permitted the creation of settled hierarchical societies with division of labour and the time to develop culture and written language while population numbers accelerated.

As a result of its long association with humans cultivated wheat has large, uniform, short, fat grains that when mature remain attached to the plant while wild wheats have small, variable, long, thin grains that are shed from the wheat ear.

In the history of wheat we can follow social and technological history as small family farms were gradually converted to vast multinational super-farms, milling was transformed from the hand-held grinding between rocks (the quern), to water mills, windmills, and then during the Industrial Revolution to mills driven by steam engine, then petrol engines, combine harvesters etc., and the replacement of long-term genetic change by selection, to complex breeding in the twentieth century, followed towards the end of the century by genetic engineering. The Great Divergence which saw European countries spread around the world assuming to dominate a global economy culminating in that of the British Empire were associated with the export of temperate agriculture.

Wheat fields are a major part of the agricultural landscapes that have replaced old forests and wild vegetation. The mozaic of geometrically enclosed pasture seen from a plane reflects the food bowl needed to maintain the population that arose because of agriculture. Whether humans domesticated wheat or wheat domesticated humans is surely a matter for debate.

First published on the internet – 1 March 2019

. . . 17 October 2022 – reorganized . . . 1 July 2023 – minor edit