Sorghum bicolor, commonly called sorghum () and also known as broomcorn, great millet, Indian millet, Guinea corn, jowar, or milo, is a species in the grass genus Sorghum. It is typically an annual, but some cultivars are perennial. It grows in clumps that may reach over 4 metres (13 ft) high. The grain is 2 to 4 millimetres (0.08 to 0.2 in) in diameter. The species originated and was domesticated in Sudan. Native to Africa and the Indian subcontinent, it is cultivated in tropical and subtropical regions for its grain. It is the world's fifth-most important cereal crop. The grain is used as food by humans, while the plant is used for animal feed and ethanol production.
Description
Sorghum is a large stout grass that grows up to 2.4 metres (8 ft) tall. It has large bushy flowerheads or panicles that provide an edible starchy grain with up to 3,000 seeds in each flowerhead. It grows in warm climates worldwide for food and forage. Sorghum is native to Africa and to the Indian Subcontinent, with many cultivated forms. Most production uses annual cultivars, but some wild species of Sorghum are perennial; the Land Institute is attempting to develop a perennial cultivar for "repeated, sufficient grain harvests without resowing". The name sorghum derives from Italian sorgo, which in turn most likely comes from 12th century Medieval Latin surgum or suricum. This in turn may be from Latin syricum, meaning "[grass] of Syria". Types include milo, durra, imphee, hegari, kaffir, feterita, shallu, and kaoliang.
Evolution
Phylogeny Sorghum is closely related to maize and the millets within the PACMAD clade of grasses, and more distantly to the cereals of the BOP clade such as wheat and barley.
History
Domestication
S. bicolor was domesticated from its wild ancestor more than 5,000 years ago in Eastern Sudan in the area of the Rivers Atbara and Gash. It has been found at an archaeological site near Kassala in eastern Sudan, dating from 3500 to 3000 BCE, and is associated with the Neolithic Butana Group culture. Sorghum bread from graves in Predynastic Egypt, some 5,100 years ago, is displayed in the Egyptian Museum, Turin, Italy. The first species to be domesticated was bicolor; it had tight husks that had to be removed forcibly. Around 4,000 years ago, this spread to the Indian subcontinent; around 3,000 years ago it reached West Africa. Four other species evolved through cultivation to have larger grains and to become free-threshing, making harvests easier and more productive. These were caudatum in the Sahel; durra, most likely in India; guinea in West Africa (later reaching India), and from that race magentiferum that gave rise to the varieties of Southern Africa. Wetter conditions in parts of the Horn of Africa between about 2,500 and 1,000 years ago supported the expansion of sorghum cultivation and contributed to the development of complex agricultural societies such as Aksum.
Spread
In the Middle Ages, the Arab Agricultural Revolution spread sorghum and other crops from Africa and Asia across the Arab world as far as Al-Andalus in Spain. Sorghum remained the staple food of the medieval kingdom of Alodia and most Sub-Saharan cultures prior to European colonialism. Tall varieties of sorghum with a high sugar content are called sweet sorghum; these are useful for producing a sugar-rich syrup and as forage. Sweet sorghum was important to the sugar trade in the 19th century. The price of sugar was rising because of decreased production in the British West Indies and more demand for confectionery and fruit preserves, and the United States was actively searching for a sugar plant that could be produced in northern states. The "Chinese sugar-cane", sweet sorghum, was viewed as a plant that would be productive in the West Indies.
Cultivation
Agronomy Most varieties of sorghum are drought- and heat-tolerant, nitrogen-efficient, and are grown particularly in arid and semi-arid regions where the grain is one of the staples for poor and rural people. These varieties provide forage in many tropical regions. S. bicolor is a food crop in Africa, Central America, and South Asia, and is the fifth most common cereal crop grown in the world. It is usually grown without fertilizers or other inputs by small-holder farmers in developing countries. They benefit from sorghum's ability to compete effectively with weeds, especially when planted in narrow rows. Sorghum actively suppresses weeds by producing sorgoleone, an alkylresorcinol. Sorghum grows in a wide range of temperatures. It can tolerate high altitude and toxic soils, and can recover growth after some drought. Optimum growth temperature range is 12–34 °C (54–93 °F), and the growing season lasts for around 115–140 days. It can grow in a wide range of soils, such as heavy clay to sandy soils with the pH tolerance ranging from 5.0 to 8.5. It requires an arable field that has been left fallow for at least two years or where crop rotation with legumes has taken place in the previous year. Diversified 2- or 4-year crop rotation can improve sorghum yield, making it more resilient to inconsistent growth conditions. Nutrients required by sorghum are comparable to other cereal grain crops with nitrogen, phosphorus, and potassium needed for growth. The International Crops Research Institute for the Semi-Arid Tropics has improved sorghum using traditional genetic improvement and integrated genetic and natural resources management practices. Some 194 improved cultivars are planted worldwide. In India, increases in sorghum productivity resulting from improved cultivars have freed up 7 million hectares (17 million acres) of land, enabling farmers to diversify into high-income cash crops and boost their livelihoods. Sorghum is used primarily as poultry feed, and also as cattle feed and in brewing.
Pests and diseases
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