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Vigna angularis (Willd.) Ohwi & H.Ohashi

Journ. Jap. Bot. 44(1): 29 (1969).
Papilionaceae (Leguminosae - Papilionoideae, Fabaceae)
Chromosome number
2n = 22
Phaseolus angularis (Willd.) W.Wight (1909).
Vernacular names
Adzuki bean, azuki bean (En). Haricot adzuki (Fr). Feijão adzuki (Po).
Origin and geographic distribution
The exact origin of adzuki bean is not known; wild types occur in Nepal, south-eastern China, Taiwan, Korea and Japan. Cultivation is known since ancient times from northern Korea, China and Japan. Adzuki bean has been introduced to many countries in the world. In Africa experimental plantings have been carried out in DR Congo, Kenya and Angola, but up-to-date information is lacking. Adzuki bean has also been recorded for Madagascar and the Seychelles.
The dried seeds of adzuki bean are eaten, either cooked whole or made into flour for use in soups, cakes, confectionery and ice cream. Adzuki bean is particularly popular in China, Taiwan, Korea and Japan (‘azuki an’), where the red seeds have a cultural value related to birth, wedding and death. Immature seeds and sprouted seeds are eaten as a vegetable. The seeds may be popped like maize grain, used as coffee substitute or eaten candied.
Adzuki bean is also grown for forage, as green manure and for soil conservation. Flour is also used for shampoos, to make facial creams and as ingredient in culture media. In China the seeds are used to treat kidney problems, constipation, abscesses, certain tumours, threatened miscarriage, retained placenta, non-secretion of milk and for improvement of blood circulation and urination. The leaves are said to lower fever and the sprouts are used to avert threatened abortion caused by injury.
Production and international trade
No statistics on the world production of adzuki bean are available. Major producers of the crop are China (670,000 ha), Japan (60,000 ha), South Korea (25,000 ha) and Taiwan (15,000 ha). Japan produces about 100,000 t/year and consumes about 140,000 t/year; it imports from China, Taiwan, the United States, Thailand and Canada. Average export from China in the 1990s was 25,000–40,000 t/year. Both the seed and the seed flour are important trade items in oriental markets.
Mature, raw adzuki bean seeds contain per 100 g edible portion: water 13.4 g, energy 1377 kJ (329 kcal), protein 19.9 g, fat 0.5 g, carbohydrate 62.9 g, dietary fibre 12.7 g, Ca 66 mg, Mg 127 mg, P 381 mg, Fe 5.0 mg, Zn 5.0 mg, vitamin A 17 IU, thiamin 0.46 mg, riboflavin 0.22 mg, niacin 2.6 mg, vitamin B6 0.35 mg, folate 622 μg and ascorbic acid 0 mg. The essential amino-acid composition per 100 g edible portion is: tryptophan 191 mg, lysine 1497 mg, methionine 210 mg, phenylalanine 1052 mg, threonine 674 mg, valine 1023 mg, leucine 1668 mg and isoleucine 791 mg. The principal fatty acids are per 100 g edible portion: linoleic acid 113 mg and oleic acid 50 mg (USDA, 2005). Adzuki bean seeds have a sweet, nutty taste.
Enzyme-resistant fractions of adzuki bean seeds have shown hypocholesterolaemic effects in rats. Hot water extracts have shown in-vivo hypoglycaemic and antitumour properties. Water extracts of the seed coat have shown hepatoprotective activity.
Annual, usually bushy and erect herb up to 90 cm tall, sometimes climbing or prostrate and rooting at the nodes; taproot 40–50 cm long. Leaves alternate, 3-foliolate; stipules small, peltate, often bifid with basal appendages; stipels lanceolate; leaflets lanceolate to ovate, 5–10 cm × 5–8 cm, acuminate, entire to 3-lobed. Inflorescence an axillary false raceme, 2–20-flowered; peduncle long in lower nodes to very short in upper nodes. Flowers papilionaceous, bisexual; pedicel short, bearing an extrafloral nectary at base; bracteoles longer than calyx; calyx campanulate, with short teeth; corolla 15–18 mm long, bright yellow, standard orbicular, wings oblong, keel turned towards the right, with a horn-shaped spur on the left side; stamens 10, 9 fused and 1 free; ovary superior, shortly hairy, style abruptly bent in upper part, hairy on one side near top, stigma lateral, discoid. Fruit a cylindrical pod 5–13 cm × 0.5 cm, pendulous, slightly constricted between the seeds, nearly glabrous, pale yellow, blackish or brown, 2– 14-seeded. Seeds cylindrical with rounded ends, flattened, 5–7.5 mm × 4–5.5 mm, smooth, wine red, occasionally buff, creamish, black or mottled. Seedling with hypogeal germination; primary leaves simple, opposite, cordate.
Vigna comprises about 80 species and occurs throughout the tropics. Vigna angularis belongs to subgenus Ceratotropis, which also includes Vigna radiata (L.) R.Wilczek (mung bean), Vigna umbellata (Thunb.) Ohwi & H.Ohashi (rice bean), Vigna mungo (L.) Hepper (black gram) and Vigna aconitifolia (Jacq.) Maréchal (moth bean). Cultivated plants of Vigna angularis have been classified as var. angularis, wild plants as var. nipponensis (Ohwi) Ohwi & H.Ohashi. Wild adzuki bean has an indeterminate growth habit with thin twining stems, small leaves, short and strongly dehiscent black to grey pods and black-mottled seeds. Numerous cultivars have been recorded within Vigna angularis, differing in time to maturity, seed colour and plant habit. Intermediate types between wild and cultivated plants, called weedy types, have been found in Japan.
The seeds of adzuki bean retain their viability for at least 5 years when stored with about 13% moisture content, at 15% relative humidity. Germination requires a soil temperature above 6–10°C, with 30–34°C being optimal. Emergence takes 7–20 days. Growth is slow compared to other pulses. Flowering lasts 30–40 days and can occur up to 3 times when planted early in the growing season. Self-pollination is predominant, but cross-pollination also occurs. The growth duration is (60–)80–120(–190) days. Nitrogen fixation levels up to 100 kg N/ha have been observed, the amount depending on soil moisture content and pH. Adzuki bean effectively nodulates with Bradyrhizobium bacteria.
Adzuki bean performs best in subtropical and warm temperate climates. It requires average temperatures of 15–30°C for optimal growth. It tolerates high temperatures but is sensitive to frost. In the tropics it is more suitable for higher altitudes. Adzuki bean grows in areas with average annual rainfall of 500–1750 mm. It is a quantitative short-day plant but day-neutral cultivars exist. Adzuki bean can be grown on a wide range of soils (pH 5–7.5), provided they are well drained.
Propagation of adzuki bean is by seed. The 1000-seed weight is 50–200 g. Sowing practices differ greatly but usually seed is sown 2–3 cm deep, in rows 30–90 cm apart and 10–45 cm within the row; sometimes it is broadcast. Seed rates vary widely (8–70 kg/ha). Because of the relatively slow growth of adzuki bean, weed control is very important, particularly between germination and flowering. Fertilizer application differs widely. An adzuki bean crop yielding 2160 kg/ha was recorded to have an uptake per ha of 74 kg N, 18 kg P and 50 kg K. Irrigation of adzuki bean is not normally done. In China adzuki bean is often intercropped with maize, sorghum and millet. In Japan adzuki bean is grown in rotation with many crops (e.g. rice, wheat, sweet potato, yam). The seed may be sown directly in rice stubble at a high rate to reduce weed problems. Numerous fungi and bacteria are known to cause diseases in adzuki bean, including powdery mildew (Erysiphe polygoni, synonym: Erysiphe betae), brown stem rot (Cephalosporium gregatum, synonym: Phialophora gregata) and bacterial blight (Xanthomonas campestris). Several insect pests, such as the adzuki pod worm (Matsumuraeses phaseoli), the Japanese butterbur borer (Ostrinia scapulalis pacifica) and cutworm (Spodoptera litura) attack the crop. Bean weevil (Callosobruchus chinensis) attacks the stored seed. In general the pods of adzuki bean do not shatter readily and the crop can be harvested with a mower or bean harvester. Traditionally, plants are cut by hand and allowed to cure on the ground for several days before being stacked into drying piles. Drying occurs until moisture content of the seed is about 16% and threshing can start. Some pods are very thin and in wet conditions seed may germinate in the pods. For hay, adzuki bean should be cut when the pods are about half mature. For seed, cutting is done when all pods are mature. Seed yields up to 3500 kg/ha are obtained. In an experimental planting in Kenya seed yields were 500–600 kg/ha.
Genetic resources and breeding
Large germplasm collections of adzuki bean are held in China (Institute of Crop Germplasm Resources (CAAS), Beijing, more than 3700 accessions) and Japan (Tokachi Agricultural Experiment Station, Hokkaido-ken, about 2500 accessions).
In China, Japan, Korea and Taiwan breeding has resulted in locally adapted better yielding cultivars, e.g. ‘Baihong No 1’ (China), ‘Erimo’ (Japan), ‘Chungwonpat’ (Korea) and ‘Kaohsiung No 3’ (Taiwan). In Japan alone more than 300 cultivars, landraces and breeding lines have been registered. In-vitro adzuki bean plants are routinely obtained using epicotyls as explants. A genetic transformation system for adzuki bean has been established using Agrobacterium-mediated transfer. A genetic linkage map has been constructed using molecular (RAPD, RFLP) and morphological markers.
Adzuki bean is a suitable crop for the subtropics and the high-altitude tropics. The potential of adzuki bean as an anti-erosion crop should not be overlooked either. Further research on its potential in the high-altitude regions of tropical Africa is recommended.
Major references
• Kay, D.E., 1979. Food legumes. Crops and Product Digest No 3. Tropical Products Institute, London, United Kingdom. 435 pp.
• Lumpkin, T.A. & McClary, D.C., 1994. Azuki bean: botany, production and uses. CAB International, Wallingford, United Kingdom. 268 pp.
• Schuster, W.H., Alkämper, J., Marquard, R., Stählin, A. & Stählin, L., 1998. Leguminosen zur Kornnutzung (Kornleguminosen der Welt). Giessener Beiträge zur Enwicklungsforschung. Reihe 2 (Monographien), Band 11. Förderverein Tropeninstitut Giessen, Giessen, Germany. CD-ROM.
• van Oers, C.C.C.M., 1989. Vigna angularis (Willd.) Ohwi & Ohashi. In: van der Maesen, L.J.G. & Somaatmadja, S. (Editors). Plant Resources of South-East Asia No 1. Pulses. Pudoc, Wageningen, Netherlands. pp. 67–69.
• Zong, X.X., Kaga, A., Tomooka, N., Wang, X.W., Han, O.K. & Vaughan D., 2003. The genetic diversity of the Vigna angularis complex in Asia. Genome 46: 647–658.
Other references
• Duke, J.A., 1981. Handbook of legumes of world economic importance. Plenum Press, New York, United States, and London, United Kingdom. 345 pp.
• Han, K.-H., Fukushima, M., Kato, T., Kojima, M., Ohba, K., Shimada, K., Sekikawa, M. & Nakano, M., 2003. Enzyme-resistant fractions of beans lowered serum cholesterol and increased sterol excretions and hepatic mRNA levels in rats. Lipids 38(9): 919–924.
• Han, K.-H., Fukushima, M., Ohba, K., Shimada, K., Sekikawa, M., Chiji, H., Lee, C.-H. & Nakano, M., 2004. Hepatoprotective effects of the water extract from adzuki bean hulls on acetaminophen-induced damage in rat liver. Journal of Nutritional Science and Vitaminology 50(5): 380–383.
• Hanelt, P. & Institute of Plant Genetics and Crop Plant Research (Editors), 2001. Mansfeld’s encyclopedia of agricultural and horticultural crops (except ornamentals). 1st English edition. Springer Verlag, Berlin, Germany. 3645 pp.
• Itoh, T., Kita, N., Kurokawa, Y., Kobayashi, M., Horio, F. & Furuichi, Y., 2004. Suppressive effect of a hot water extract of adzuki beans (Vigna angularis) on hyperglycemia after sucrose loading in mice and diabetic rats. Bioscience Biotechnology and Biochemistry 68(12): 2421–2426.
• Itoh, T., Umekawa, H. & Furuichi, Y., 2005. Potential ability of hot water adzuki (Vigna angularis) extracts to inhibit the adhesion, invasion, and metastasis of murine B16 melanoma cells. Bioscience Biotechnology and Biochemistry 69(3): 448–454.
• Kaga, A., Ohnishi, M., Ishii, T. & Kamijima, O., 1996. A genetic linkage map of azuki bean constructed with molecular and morphological markers using an interspecific population (Vigna angularis × V. nakashimae). Theoretical and Applied Genetics 93(5/6): 658–663.
• USDA, 2005. USDA national nutrient database for standard reference, release 18. [Internet] U.S. Department of Agriculture, Agricultural Research Service, Nutrient Data Laboratory, Beltsville, Maryland, United States. Accessed September 2005.
• Yamaguchi, H., 1992. Wild and weed azuki beans in Japan. Economic Botany 46(4): 384–394.
• Yamada, T., Teraishi, M., Hattori, K. & Ishimoto, M., 2001. Transformation of azuki bean by Agrobacterium tumefaciens. Plant Cell, Tissue and Organ Culture 64: 47–54.
Sources of illustration
• van Oers, C.C.C.M., 1989. Vigna angularis (Willd.) Ohwi & Ohashi. In: van der Maesen, L.J.G. & Somaatmadja, S. (Editors). Plant Resources of South-East Asia No 1. Pulses. Pudoc, Wageningen, Netherlands. pp. 67–69.
P.C.M. Jansen
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
Based on PROSEA 1: ‘Pulses’.

M. Brink
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
G. Belay
Ethiopian Agricultural Research Organization, Debre Zeit Center, P.O. Box 32, Debre Zeit, Ethiopia
Associate editors
J.M.J. de Wet
Department of Crop Sciences, Urbana-Champaign, Turner Hall, 1102 South Goodwin Avenue, Urbana, IL 61801, United States
O.T. Edje
Faculty of Agriculture, University of Swaziland, P.O. Luyengo, Luyengo, Swaziland
E. Westphal
Ritzema Bosweg 13, 6706 BB Wageningen, Netherlands
General editors
R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
L.P.A. Oyen
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
Photo editor
A. de Ruijter
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article:
Jansen, P.C.M., 2006. Vigna angularis (Willd.) Ohwi & H.Ohashi In: Brink, M. & Belay, G. (Editors). PROTA 1: Cereals and pulses/Céréales et légumes secs. [CD-Rom]. PROTA, Wageningen, Netherlands.
Distribution Map 1, fruiting branch; 2, flower; 3, seed.
Source: PROSEA