Vigna umbellata (PROSEA)
Vigna umbellata (Thunb.) Ohwi & Ohashi
- Protologue: Jap. Journ. Bot. 44: 31 (1969).
- Family: Leguminosae
- Chromosome number: 2n= 22
- Phaseolus calcaratus Roxb. (1832),
- Vigna calcarata (Roxb.) Kurz (1876),
- Azukia umbellata (Thunb.) Ohwi (1953).
- Rice bean (En)
- haricot riz (Fr)
- Burma: pé-yin
- Indonesia: kacang uci
- Malaysia: kacang sepalit
- Philippines: anipai, kapilan, pagsei
- Thailand: thua daeng, thua pae, ma pae
- Cambodia: sândaêk ângkât miëhs, sândaêk riech mieh
- Laos: thwàx la:ng tê:k, thwàx sadê:t pa:x, thwàx phi:
- Vietnam dâu gao.
Origin and geographic distribution
Rice bean is a native of South and South-East Asia. It is most widely cultivated in China, Korea, Japan, India, Burma, Indonesia, Malaysia, Fiji, the Philippines and Mauritius and to a limited extent in the tropical parts of all continents.
Rice beans are usually boiled and eaten with or instead of rice. The young pods and leaves and sprouts are used as vegetable. The whole plant is used as fodder, as a cover crop, as green manure and as living hedge. In Perak (Malaysia) the leaves are used with rice-flour in a poultice applied to the abdomen for stomach-ache.
Production and international trade
Rice bean rarely enters international trade, but it is extensively grown for human food in Asia and the Pacific Islands. In 1975 Japan imported 12 000 t, 7 000 t from Thailand, 3 000 t from China and 2 000 t from Burma.
Per 100 g edible portion, dry seeds contain: water 13.3 g, protein 20.9 g, fat 0.9 g, carbohydrates 64.9 g, fibre 4.8 g, ash 4.2 g. The energetic value averages 1373 kJ/100 g. Seed weight varies between 8 and 12 g/100 seeds.
- Annual vining herb with erect, suberect or flexuose stem, 30-75 cm tall, usually clothed with fine, deciduous, deflexed hairs; vines grooved, 1-3 m long.
- Leaves trifoliolate, stipules lanceolate, petioles 5-10 cm long; leaflets broadly ovate to ovate-lanceolate, 5-10 cm x 2.5- 6 cm, membranous, subglabrous, usually entire, sometimes trilobed.
- Inflorescences erect axillary racemes, 5-10 cm long, with 5-20 flowers, peduncles up to 20 cm long; flowers bright yellow, 2-3 together, up to 2 cm in diameter, with large bracteoles.
- Pods long and slender, partly falcate, 6-13 cm x 0.5 cm, glabrous, with 10-16 seeds.
- Seeds oblong to strongly elongate, subtrapezoidal, 5-10 mm x 2-5 mm, smooth, dark red, green, yellow, brown, black, speckled or mottled.
Growth and development
Germination is hypogeal. Seedlings grow vigorously and establish themselves early. The plants can smother weeds. The crop matures in 60-150 days. In the Philippines days to flowering averages 64, to maturity 92; in India early maturing types behave likewise, late types ripen in 130-150 days. Flowers are self-fertile, but cross-pollination occurs as well. All pods mature rather simultaneously.
Other botanical information
At present two botanical varieties are distinguished: var. umbellata, the cultivated forms, and var. gracilis (Prain) Maréchal, Mascherpa & Stainier, the original wild forms with slender branchlets, narrow leaflets and long peduncles. Many cultivars exist.
Rice bean is suited to the lowland humid tropics, but some cultivars are also adapted to subtropical or subtemperate conditions. It grows best at average temperatures between 18 and 30 °C and prefers a rainfall of 1000-1500 mm/year. The crop can be grown in the tropics up to an altitude of 2000 m. Rice bean is a quantitative short-day plant. The threshold is less than 12 hours. In West Bengal the maximum and minimum temperatures of flower initiation is found to be 25-26 °C and 10-12 °C respectively. Rice bean grows best on fertile loams. It tolerates high temperatures and moderate drought, but it is frost susceptible.
Propagation is by seed. Rice bean is usually sown broadcast, after two or three ploughings. It can also be planted in rows 90 cm apart. In India the seed rate is 40-50 kg/ha (if grown for seed), or 60-70 kg/ha (if grown as a catch crop for fodder). In Burma average seed rate is 21 kg/ha. In North-Eastern India it is grown under shifting cultivation with maize and millet. Its forage quality is improved when grown in mixture with the annual grass Pennisetum pedicellatum.
The crop receives little aftercare. In India application of 50-60 kg/ha superphosphate is recommended. In Burma rice bean is usually grown in rotation with rice.
Diseases and pests
Relatively speaking rice bean is a pest-free crop. Powdery mildew, rust and cucumber mosaic virus can attack the crop in the Philippines. Nematode problems are reduced by flooding, hence rotation with rice is recommended.
The viny plant habit and the shattering of pods make rice bean difficult to harvest. Harvesting in the morning, when the pods are moist, reduces the losses. If grown for fodder, rice bean should be harvested when the pods are half developed, since the leaves drop easily when the plant reaches maturity.
Average seed yield is 200-300 kg/ha, although in West Bengal, with good crop management, yields up to 2240 kg/ha were obtained. In Burma yield averages 420-840 kg/ha, in Papua New Guinea 500-800 kg/ha. Forage yield is 2200-3500 kg/ha.
Handling after harvest
The seeds are dried in the sun and threshed by hand. Usually the seeds are not affected by storage insects.
Genetic resources and breeding
Germplasm collections are available in India and Taiwan (AVRDC), but more collections are needed. The breeding of quick-maturing, day-neutral, high-yielding and non-shattering, erect cultivars, that are nematode-resistant are the most urgent research needs. Moreover, all agronomical aspects need investigation, e.g. time of sowing, plant density, fertilizer requirements.
Rice bean is a pulse crop whose development is handicapped by the fact that average yields are low and seed-pods shatter easily, making economic harvesting difficult. Its tolerance of high temperatures and humidities, its adaptation to heavy soils, its quick growth, its resistance to pests and diseases and its nutritious seeds make rice bean a valuable crop that deserves testing throughout the tropics. There has been increasing interest in India in the development of rice bean as a fodder crop, and now as a grain crop, and also in West Africa, where it is less susceptible to pests and diseases than many other grain legumes.
- Arora, R.K., Chandel, K.P.S., Joshi, B.S. & Pant, K.C., 1980. Rice bean: tribal pulse of eastern India. Econ. Bot. 34 (3): 260- 263.
- Chandel, K.P.S., Arora, R.K. & Pant, K.C., 1988. Rice bean - a potential grain legume. NBPGR, New Delhi, India. Scientific Monograph No. 12. 60 pp.
- Kay, D.E., 1979. Food legumes. TPI Crop and Product Digest No. 3. Tropical Products Institute, London. p. 348-354.
- Mukherjee, A.K. & Roquib, M.A., 1980. Herbage and grain yield potentiality of rice bean (Vigna umbellata (Thunb.) Ohwi & Ohashi) - A review. Forage Res. 6: 165-170.
- C.C.C.M. van Oers