Agroforestree Database

Local names:
 Amharic (yergib ater,yewof ater), Burmese (pe-sinngon,pay-in-chong), English (Congo pea,pigeon pea,no-eye pea,red gram,angolan pea,yellow dhal), Filipino (kadios,kardis,tabios,kidis), French (ambrévade,pois pigeon,pois d’Angole,pois cajon), German (angli

Cajanus cajan is a glandular-pubescent, short-lived perennial (1-5 years) shrub, usually grown as an annual, 0.5-4 m high, with thin roots up to 2 m deep; stems up to 15 cm in diameter; branches many, slender. 

Leaf rachis 1-2 cm long; petiole half as long or less; stipules acuminate, 2.5-5 mm long, persistent; leaflets lanceolate or narrowly elliptic, puberulent above and underside, the largest to 7.5-8 x 2.8-3.5 cm, acute apically, bases similar, venation strongly reticulate, prominent underneath.

Inflorescence axillary from a single peduncle, terminating at the insertion of 1-2 pedicels or continuing for 1-3 additional nodes, rarely branching, usually slightly shorter than the leaves, mostly with 2-6 flowers; bracts about 5 mm long; flowers about 2 cm long; pedicels to about 9 mm long; calyx tube 3-5 mm long, glandular and pubescent, the upper lobe bifid, the lower lobe longest, about 4 mm long; vexillary petal basally inflexed biauriculate, mostly with reddish striate, bicallose in the target area, glabrous, about 14 mm long, with a claw about 4 mm long.

Fruit a pod, linear-oblong, apex obtuse or acute, compressed, bivalved, depressed between the seeds, about 4 cm long, 1 cm wide, 3-4 mm thick; upper suture swollen, the lower indistinct; beak downcurved; seeds 1-5, compressed, about 6 x 4 x 1.5 mm, of various colours; the hilum linear-oblong to somewhat elliptic, about 3 mm long.

Ecology

As the species is not found truly in the wild, its natural habitat conditions are uncertain. It prefers grassy habitats in tropical, cold-free zones with optimum 600-1000 mm annual rainfall. However, it grows in humid areas with 2500 mm annual rainfall and in semi-arid areas with only 400 mm of rain annually.

Native range
India, Indonesia, Myanmar, Pakistan

Tree management

For hedgerow intercropping, the hedges should be cut at height of 0.5-1 m when the grain crop is fully mature. The hedges can be cut 2-3 times a year in areas where the dry season lasts 4-6 months. At pod maturity, branches of C. cajan are cut at about 0.5 m. Higher levels of pruning can result in higher and unacceptable levels of plant mortality. As a field crop, C. cajan may be typified as rather undeveloped; the tall genotypes particularly are cumbersome in cultivation. Weeds must be controlled to alleviate slow initial growth. Wind may bend the plants, but staking is not practised. In intensive cropping of short-duration cultivars, irrigation may be required. C. cajan’s response to fertilizers is rarely economic; a phosphate dressing is generally recommended at 20-100 kg/ha.

Seed storage behaviour is orthodox with no problems for long-term storage under preferred conditions. There are 5000-14 000 seeds/kg.

As the species is not found truly in the wild, its natural habitat conditions are uncertain. It prefers grassy habitats in tropical, cold-free zones with optimum 600-1000 mm annual rainfall. However, it grows in humid areas with 2500 mm annual rainfall and in semi-arid areas with only 400 mm of rain annually.

The pods are picked when the seed has reached physiological maturity and is just beginning to lose its bright green colour. C. cajan is best established by direct seeding in a well-prepared field. No pregermination treatment of seeds is needed. Seedlings have hypogeal germination. Emergence is complete 2-3 weeks after sowing. Stem cuttings rarely succeed.

Erosion control:  Extensively covering the ground with C. cajan prevents soil erosion by wind and water.

  The seeds of C. cajan can be used as a vegetable. Very young pods are harvested before the seeds are distinct and are cooked in curries or used to make relishes. The dry seeds have several products such as tempe (a traditional Indonesian food prepared by fermenting with a Rhizopus mould then soaked, dehulled and cooked legume seeds), and ketchup (pigeonpea sauce, a replacement for soy sauce in Indonesia that is made by fermenting C. cajan with Apergillus oryzae). C. cajan flour (mixed with wheat to improve the protein level of baked products) and clear noodles of a quality higher than that of mung bean are made from dehulled seed. Fresh seeds contain vitamins, especially provitamin A and vitamin B complex. Per a 100 g edible portion, dry seeds contain 7-10.3 g water, 14-30 g protein, 1-9 g fat, 36-65.8 g carbohydrates, 5-9.4 g fibre and 3.8 g ash. The energy content averages 1450 kJ/100 g.

C. cajan fodder alone may be a bit low in energy. The leaves can provide a good substitute for alfalfa in animal feed formulations, particularly in areas not suitable for alfalfa. The pods are used as cattle feed but are limited by their low protein and high fibre content. They have therefore been used as a roughage source for cattle. C. cajan grain has been successfully used for poultry feed. In Hawaii, a mixture of equal quantities of cracked pigeonpea and cracked maize has been proved the best poultry ration.

Apiculture:  Honeybees collect nectar from the plant, which is an important honey source. The honey has a distinctive greenish hue in the comb.

C. cajan sticks are an important household fuel in many areas. The heat value is about 1/2 that of the same weight of coal, and it has several advantages over traditional trees, such as its rapid growth potential, possibility of producing other crops on the same land, and production of a seed crop. Farmers sow it instead of grain because of its wood. Its productivity levels more than make up for the comparatively poor fuel characteristics.

Fibre: On an experimental basis, C. cajan has been found to produce a pulp for paper similar to that of hardwoods, and the pulp might be suitable for making good-quality writing and printing paper. The branches and stems can be used for making baskets.

Timber:  The wood is used in light construction such as in roofing, wattling on carts, tubular wickerwork lining for wells and baskets. 

Shade or shelter:  C. cajan is useful as a tall hedge on dry soil and on the bunds of paddy fields. It is often grown as a shade crop, cover crop or windbreak. 

Medicine:  It has many traditional uses as medicine. In Java, for example, the young leaves are applied to sores, herpes and itches.

Nitrogen fixing:  Using the nitrogen-balance method, it has been proved in northern India that long-duration C. cajan can fix up to 200 kg N/ha over a 40-week period.

In Southeast Asia, C. cajan is grown as a support for vanilla.

Soil improver:  The root system is reported to break plough pans, thus improving soil structure, encouraging infiltration, minimizing sedimentation and smothering weeds. Leaf fall at maturity adds to the organic matter in the soil and provides additional nitrogen. It seems to have special mechanisms to extract phosphorus from black Vertisol soils.

Intercropping:  Due to its hardiness, ability to grow on residual soil moisture, and slow early growth, C. cajan is an ideal, non-competitive crop to plant with cereals. In traditional cropping systems, it is mixed with cereals, oil seeds, short-season pulses or cotton, with the cereal as the main crop and C. cajan as the bonus crop. In Kenya, it is an important food legume, cultivated commercially for dry seed and as a green vegetable. In Zambia, smallholder farmers generally grow it in their backyards and around the fields of annual crops. In Uganda, it is combined with millet in a cropping system.