Common Name: Cluster Bean

General Information

Cyamopsis tetragonoloba is an erect, herbaceous annual to perennial plant growing up to 300cm tall, though cultivated forms are more commonly 20 - 100cm tall[].
The plant is the source of guar gum, obtained from the seeds and used extensively in the food industry, commercially and medicinally. The plant is also a local source of food. It is often cultivated in India and southeastern Asia for its seeds and seedpods, which are also used as a food[, ].

Known Hazards

The immature seedpods contain high contents of hydrocyanic acid, though by the time the pods mature this has been reduced to a trace[].

Botanical References

Range

E. Asia - India.

Habitat

Not known in a wild state.

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Perennial
Height	2.00 m
Cultivation Status	Cultivated

Cultivation Details

Cyamopsis tetragonoloba is suitable for growing in the warm temperate zone as an annual, although it is more commonly grown in lowland tropical and subtropical areas up to an elevation of 1,000 metres[]. Tolerating high temperatures, it requires a high level of solar radiation in order to do well[]. Grows best when the soil temperature is in the range of 25 - 30°c, bur able to tolerate temperatures to 45°c[, ]. Prefers an annual rainfall in the range of 500 - 800mm, but can tolerate up to 2,700mm[, ]. Dry weather is essential once fertilization has taken place - the developing pods can be damaged by high humidity or rainfall[].
Prefers a sunny position[]. Grows best in alluvial and sandy loam soils[]. Established plants are very drought resistant[]. Some forms are tolerant of poor soils, alkaline or saline conditions[]. Prefers a pH in the range 7.5 - 8, tolerating 5.5 - 8.5[, ].
Young pods can be harvested 2 - 3 months after sowing the seed[].
Yields of 6 - 8 tonnes per hectare of the pods have been obtained[]. Approximately 800kg of dried seed per hectare is considered average[].
There are some named varieties[, ]. Many cultivars are daylength sensitive, though many new cultivars are daylength neutral[].
The plant has a vigorous taproot[].
This species has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby[].

Edible Uses

Leaves - cooked as a vegetable[].

Seed - cooked[]. Rich in protein[]. The seeds can also be sprouted and eaten[]. The seeds are about 5mm long[]. Mainly used in times of shortage when other, more preferred foods, are not available[].

Seedpods - cooked[]. Sweet and tender[]. The unripe seedpods are eaten in curries, fried, salted, or dried for later use[]. The pods are 4 - 10cm long[]. Unripe pods need to be thoroughly cooked in order to destroy a toxic principle[]. Only traces of this toxin remain in mature pods[].

The seeds are used to make guar gum, which is much used by food manufacturers as a stabilizer and thickener in ice creams, bakery goods, gluten-free foods etc[]. Guar seed is an important source of the industrial vegetable gum galactomannan, which has a thickening property 5 - 8 times stronger than starch. It is used as a thickener and stabilizer in foods such as salad dressings, ice cream, yoghurt, tinned vegetables and bakery items[].

Medicinal

The seeds are dried, ground into a powder then mixed with water to form a viscous substance known as guar gum[]. This comprises about 86% water-soluble mucilage consisting of mainly galactomannin[]. Guar gum is gently laxative, helps to lower blood cholesterol levels and acts as a digestive tonic[].
The gum is taken internally as an effective but very gentle bulk laxative[]. It also delays the emptying of the stomach and thereby slows the absorption of carbohydrates, thus helping to stabilize blood sugar levels[]. This can be of great importance to people with blood sugar level problems, such as diabetics and pre-diabetics[].

Traditionally, the leaves are eaten to cure night blindness[].

Agroforestry Uses:

The plant is grown as a green manure and cover crop, and also as a shade plant for ginger and turmeric[, ].
It is often grown as an intercrop with other annuals such as pearl millet, sorghum, maize or cotton. It is also grown as a cover crop between young rubber or young coconut trees. As a sole crop it is grown in rotation with maize, sorghum, cotton, wheat and vegetables[].

Other Uses

Guar seed is an important source of the industrial vegetable gum galactomannan, which has a thickening property 5 - 8 times stronger than starch. It is used as a size to strengthen cloth and paper; in cosmetics; as a filtering agent in the mining industry; and as an additive to drilling fluids in oil-well drilling[, ].

Propagation

The seed has a hard seedcoat and may benefit from scarification before sowing in order to speed up and improve germination. This can usually be done by pouring a small amount of nearly boiling water on the seeds (being careful not to cook them!) and then soaking them for 12 - 24 hours in warm water. By this time they should have imbibed moisture and swollen - if they have not, then carefully make a nick in the seedcoat (being careful not to damage the embryo) and soak for a further 12 hours before sowing.
Inoculating the seed with Rhizobium bacterium may be necessary in order for the plant to establish and perform well[].