Vigna angularis (PROSEA)
Vigna angularis (Willd.) Ohwi & Ohashi
- Protologue: Jap. Journ. Bot. 44: 29 (1969).
- Family: Leguminosae
- Chromosome number: 2n= 22
- Phaseolus angularis (Willd.) W.F. Wight (1909).
- Adzuki bean (En)
- haricot adzuki (Fr).
Origin and geographic distribution
Adzuki bean is probably a native of Japan, but has long been established in China and Sarawak. It is not known in the wild. It has been cultivated for long in Japan, Korea, Manchuria, India and neighbouring areas of South Asia, and has been introduced to Hawaii, southern USA, Angola, Zaire, Kenya, Thailand, New Zealand and South America.
The dried pulse is used as a human food, either cooked whole or made into a meal used in soups, cakes or confections. Sprouted beans are used as a vegetable. Beans may be popped like corn, used as a coffee substitute or eaten candied. The crop is also grown for forage and green manure. Flour is also used for shampoos and to make facial cream. In China the beans are used to treat diseases like kidney trouble, constipation, abcesses, certain tumors, threatened miscarriage, retained placenta and nonsecretion of milk. The leaves are said to lower fever and the sprouts treat threatened abortion caused by injury.
Production and international trade
No data for the global production of adzuki bean are available. Adzuki bean and adzuki bean flour are both important items of trade on oriental markets. China, Korea, Colombia and Thailand are the main exporters. Japan is the main producer (1970/74: average 123 000 t/year) and consumer (1970/74: average 27 875 t/year), where it is second to soyabean and commands highest prices.
Per 100 g edible portion dry seeds contain: water 10.8 g, protein 19.9 g, fat 0.6 g, carbohydrates 64.4 g, fibre 7.8 g, ash 4.3 g. The energetic value averages 1411 kJ/100 g. Seed weight varies between 10 and 20 g/100 seeds.
- An annual herb, usually bushy and erect, 25-90 cm tall, sometimes slightly vining or prostrate. Roots with many nodules.
- Leaves trifoliolate; leaflets ovate, usually entire, 5-9 cm long.
- Inflorescence axillary, short, with 6-12 clustered flowers.
- Flowers bright yellow. Pods cylindrical, 6-12.5 cm x 0.5 cm, straw coloured, blackish or brown, 6-14 seeded.
- Seed cylindrical to cordate, rounded-four-sided to subtrapeziform or rectangular with rounded ends, 5-7.5 mm x 4-5.5 mm, smooth, wine red, occasionally buff, creamish, black or mottled.
The seeds retain their viability for over 2 years. Germination is hypogeal. The growth period is 60-120 days. More than 60 cultivars have been recorded, differing in time of maturity, colour of seed and plant habit. Cross-pollination between cultivars is frequent. The distinction of var. angularis for the cultivated plants and var. nipponensis (Ohwi) Ohwi & Ohashi for the primitive (wild?) plants is artificial.
Adzuki bean requires soil temperatures above 16 °C for germination and 15-30 °C for good growth. The crop tolerates annual precipitation of 530-1730 mm, an annual mean temperature of 8-30 °C and a pH of 5-7.5. Adzuki bean is a quantitative short-day plant.
Propagation is by seed. Seed is sown 2.5 cm deep in rows 60-90 cm apart, plants 30 cm apart. Seeding rates vary from 8 to 30 kg/ha. In Japan adzuki beans are cultivated in rotation with rice grown in rows. Elsewhere the seed is sown directly in the rice stubble at a high rate, reducing the weed problem. In Japan several insect pests, like the adzuki pod worm, the Japanese butter bean borer and cutworms attack the crop. Several fungi and bacteria are known to cause diseases in adzuki bean: bacterial blight, leaf spot, leaf blotch, rust. Bean weevil, Callosobruchus chinensis, can attack the seed during storage. In general the pods do not shatter readily: the crop can be harvested with a mower or bean harvester. 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 can vary between 90-2500 kg/ha. In Taiwan it is 1450 kg/ha, in Japan 1900 kg/ha, in Kenya 500-600 kg/ha, in New Zealand 1340-2240 kg/ha.
Genetic resources and breeding
Unknown in the wild, germplasm of adzuki beans has to be collected from the regions of cultivation in India, China and Japan. In Japan breeding has resulted in several high yielding cultivars, like 'Benidainagon', 'Chungjupat', 'Hatsune chouzou' and 'Erimo-shozu'.
Adzuki bean is a suitable crop for the subtropics and the high altitude tropics. Although it is a valuable pulse the potential of adzuki bean as an anti-erosion crop should not be overlooked. Its tolerance to drought, frost, heat and virus diseases makes it an interesting crop, deserving more attention.
- Duke, J.A., 1981. Handbook of legumes of world economic importance. Plenum Press, New York and London. p. 288-291.
- Sacks, F.M., 1977. A literature review of Ph. angularis - the adzuki bean. Econ. Bot. 31 (1): 9-15.
- C.C.C.M. van Oers