Macrotyloma uniflorum (PROSEA)
 |
Introduction |
Macrotyloma uniflorum (Lam.) Verdc.
- Protologue: Kew Bulletin 24: 322, 401 (1970).
- Family: Leguminosae
- Chromosome number: 2n= 20, 22, 24.
Synonyms
- Dolichos uniflorus Lam. (1786)
- Dolichos biflorus auct. mult., non L.
Vernacular names
- Horse gram (En)
- Grain de cheval (Fr)
- Indonesia: kekara
- Burma: pè-bi-zât.
Origin and geographic distribution
Horse gram is native to the Old World tropics. It is extensively cultivated in the drier areas of Australia, Burma, Sri Lanka, the Himalayas, Africa and America, and especially in India.
Uses
As a pulse, the seeds are eaten poached, boiled or fried, whole or ground. In Burma, boiled seeds are pounded with salt and fermented, which results in a product similar to soya sauce.
All parts are used as fodder and as green manure. Its use as fodder is gaining ground in Australia and South-East Asia.
In traditional medicine, the seeds are said to be used as an astringent, diuretic and tonic.
Production and international trade
For the period 1968-1972, production in India has been estimated to be 377 000 t/year. Most is produced for domestic consumption. International trade is of no importance.
Properties
Per 100 g edible portion seeds contain: water 8-12 g, protein 22-25 g, fat 0.5-5 g, carbohydrates 57-60 g, fibre 5 g, ash 3 g. Energy content averages 1400 kJ/100 g. Seed weight is about 1.5 g/100 seeds.
Botany
- A low-growing, slender, suberect annual or perennial herb with slightly twining downy stems and branches, 30-60 cm high.
- Leaves trifoliolate; leaflets broadly ovate, 2.5-5 cm long.
- Flowers 1-3 together on short axillary peduncles; corolla pale yellow.
- Pod linear, 3-5 cm long, recurved, beaked, downy, dehiscent, with 5-7 seeds.
- Seeds small, rhomboid, 3-6 mm long, flattened, light red, brown, black or mottled.
- Horse gram is self-fertile.
Four varieties are distinguished.
- var. uniflorum: pods 6-8 mm wide. Native of lndia. Widely cultivated in the tropics as cover and forage crop;
- var. stenocarpum (Brenan) Verdc.: pods 4-5.5 mm wide; leaflets pubescent; sutures of pods not warted. Wild plant in Acacia bushland and thicket in Africa and India;
- var. verrucosum Verdc.: pods 4-5.5 mm wide; leaflets pubescent; sutures of pods obscurely to markedly warted. Wild plant in grassland in Kenya, Tanzania and Mozambique;
- var. benadirianum (Chiov.) Verdc.: pods 4-5.5 mm wide; leaflets densely velvety; sutures of pods slightly warted. Wild plant in sand dunes of Somalia and Kenya.
Ecology
Horse gram is a short-day plant. It requires an average temperature of 20-30 °C and is completely intolerant of frost. It is grown as a dry-land crop in areas with rainfall less than 900 mm/year; in high rainfall areas, it is sown in the dry season. It does not tolerate waterlogging. It does well on light sandy soils, red loams, black cotton loams and stony and gravelly upland soils with pH 5-7.5. In India, it is grown up to altitude 1800 m.
Agronomy
Horse gram is propagated by seed. Seeds are broadcast or sown 1-2.5 cm deep in rows 90 cm apart at a rate of 25-45 kg/ha. It does best in a well prepared seed-bed but will establish in soil that has hardly been disturbed.
It is usually grown as a sole crop but intercropping is possible, for instance with Guizotia, Eleusine, Lens, castor beans, groundnuts or maize. It can also easily be established in natural pastures. The crop requires little attention. Its vigorous growth tends to smother weeds.
The most serious diseases in India are a root-rot caused by Rhizoctonia sp. and anthracnose (black sunken spots on stems, leaves, seeds and pods) caused by Glomerella lindemuthianum. The gram leaf caterpillar Azazia rubricans is destructive.
The crop matures in 4-6 months for seed. For forage, harvest can start 6 weeks after sowing. For seed production, the plants are eut when the pods are dry, stacked and dried in the sun for 7 days. Plants are then threshed by flailing with sticks, by stone rollers or in India by treading with oxen. Seed requires thorough winnowing and sieving as weed content is usually high.
For seeds, yield averages 130-900 kg/ha in India, 1120-2240 kg/ha in Australia; for green forage expressed as dry matter, 5-14 t/ha in India, 4.4 t/ha in Australia.
Genetic resources and breeding
The cultivated crop is usually a mixture of several landraces with different seed colours and periods of maturity. Breeding is focused on day-neutral cultivars with high yield potential. Wild relatives are the three varieties mentioned under Botany.
Prospects
For dry areas, horse gram is an interesting crop because of its rapid growth, its heavy seeding habit and its drought tolerance. In Australia, its use as fodder is restricted because of its short life and its loss of leaf in autumn and winter.
Literature
- Duke, J.A., 1981. Handbook of legumes of world economic importance. Plenum Press, New York and London. p. 146-149.
- Kay, D.E., 1979. Food legumes. Tropical Products Institute, London. Crop and Product Digest No 3, p. 177-183.
Authors
- P.C.M. Jansen
