Common Name: Sorghum

General Information

Sorghum bicolor is a vigorous, erect, annual grass with one to many tillers. A very variable plant, it can grow up to 5 metres tall.
A staple food in the hot, dry tropics, sorghum is the fifth most commonly grown cereal in the world. It has a very long history of being utilised by humans, dating back to at least 1,000 BC[, ]. It is widely cultivated in tropical and warm temperate zones for its edible seed, as well as for its panicles (which are used as brooms) and the syrup obtained from its sap.

Known Hazards

The immature plant is poisonous, especially if slightly wilted, since it can contain the toxins hydrogen cyanide and the alkaloid hordenine[, , ]. These substances are destroyed if the plant is dried or made into silage[]. In small quantities, hydrogen cyanide has been shown to stimulate respiration and improve digestion, it is also claimed to be of benefit in the treatment of cancer. In excess, however, it can cause respiratory failure and even death.

Botanical References

,

Range

Original habitat is obscure, but it is likely to have been Africa to the Indian Subcontinent.

Habitat

Not known in the wild.

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Annual
Height	5.00 m
Growth Rate	Fast
Pollinators	Self, Wind
Self-fertile	Yes
Cultivation Status	Cultivated

Cultivation Details

Sorghum bicolor is a plant of the tropics and subtropics, where it is found main in semi-arid areas and at elevations up to 2,500 metres. It is also cultivated in many areas of the temperate zone, especially where the summers tend to be hot. It grows best in areas where annual daytime temperatures are within the range 22 - 35°c, but can tolerate 8 - 40°c[].It prefers a mean annual rainfall in the range 400 - 600mm, but tolerates 300 - 700mm[].
A fairly easily grown plant, requiring a warm, sheltered and sunny position[], preferring a slightly to moderately acid soil[, ], though some cultivars have succeeded with a pH as high as 8[]. Plants are adapted to a wide range of soils varying from light loams to heavy clays, they thrive best on light, easily worked soils of high fertility, with moderate to high availability of water[]. Moderately well-drained soils are suitable for sorghums[]. Prefers a pH in the range 5.5 - 7.5, tolerating 5 - 8[]. Small amounts of alkali in sand reduces performance considerably[]. Plants are moderately tolerant of saline soils[]. Established plants are very drought resistant, they succeed in arid and nutrient-poor soils[]. A nitrogen rich soil causes the plants to lodge[].
Yields of around 6 tonnes per hectare have been achieved, though yields as low as 200 kilos have been reported - yields below 2 tonnes are not considered financially viable[].
There are many named varieties[, , , , ].
There is a multiplicity of forms of cultivated sorghum, derived by human selection and all fully interfertile. Some forms have sweet culms. Many species names have been proposed in the past in an attempt to categorize this variation, but they represent no more than intergrading cultivars within the common species pool[].
Some cultivars are short-day plants and are unlikely to produce flowers and seed away from the tropical zone[].

Edible Uses

Seed - raw or cooked. It is used as a whole grain in similar ways to rice, it can be popped much like popcorn, or can be ground into a flour and made into bread etc[, , , , ]. The ground seed yields a particularly white flour[]. Sorghum is a staple food in some regions, where it is often fermented (lactic acid fermentation) before being eaten[]. The sprouted seed can be eaten raw, and is sometimes added to salads[]. The seed is germinated, then dried and ground into a powder to form malt, which is used as a substratum for fermentation in local beer production[].

Stems - cooked[]. Some caution is advised here, there are some reports that the leaves can contain the poison cyanide[].
The stems of sweet sorghum types are chewed like sugar cane and, mainly in the United States, a sweet syrup is pressed from them[].
Sap - raw or cooked. Very sweet, it is made into a syrup[, , , , ].

Medicinal

The decoction of the seed is demulcent and diuretic[]. It is used in the treatment of kidney and urinary complaints[, ].

The inflorescence is astringent and haemostatic[]. The leaves and panicles are included in plant mixtures for decoctions used in the treatment of anaemia[].

Decoctions of the twigs, combined with lemon, is used as a treatment against jaundice[].

The red pigment is said to have antimicrobial and antifungal properties. It is used as a treatment for anaemia[].

Other Uses

The flowering panicles, especially of cultivars specially bred for the purpose, are used as brushes, brooms, whisks etc[, , , , ].

Several non-edible sorghum cultivars are exclusively grown for the red pigment present in the leaf sheaths and sometimes also in adjacent stem parts. It is used as a dye for mats, textiles, strips of palm leaves and grasses used in basketry and weaving, ornamental calabashes, wool, as a body paint and to colour cheese and lickstones for cattle[].
A similar dye can be extracted from the grain refuse (glumes and grain wall) of several red sorghum cultivars grown for food or for beer-making[]. The red sorghum dyes were traditionally used as a funeral hanging, decorated with patterns made by thick threads added to the weft of the fabric. The fabrics in which the dominant colours were derived from sorghum were known as ‘ifala’. Sorghum is also used to provide the violet colours decorating the masks worn during certain dances. Sorghum and other tannin-rich dyes are used in combination with mud to create the patterns of the painted cloths produced in the Korhogo region.
The dye was extracted by squeezing out the juice, which was then fermented. Used with wool or silk mordanted with tin or chrome, the result was a colourfast red-brown. Recently the use of sorghum dye in hair dying products has been patented[].

Sorghum flour is used to produce an adhesive that is used in the manufacture of plywood[].

Stems are used for weaving fences, mats, wattle houses etc[]. Sorghum plant residues are used extensively as material for roofing, fencing, weaving and as fuel[].

The plant is an excellent source of biomass[]. The stems can be used for the production of fibre board. Danish scientists have made good panelling using stem chips of sorghum[].

Propagation

Seed - sow mid spring in a greenhouse and only just cover the seed. Germination should take place within 2 weeks if given a minimum germination temperature of 23°c[]. Prick out the seedlings into individual pots once they are large enough to handle and plant them out after the last expected frosts. Consider giving them some protection, such as a cloche, until they are growing away strongly.