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Azuki bean [Vigna angularis (Wild.) Ohwi et Ohashi]


The situation in Japan and information from the NIAS genebank
Azuki bean is an ancient and important crop in Japan. The written record of azuki bean has appeared in "Kojiki" and "Nihonshoki" (8th century) (Hoshikawa 1981).
Various landraces have been developed. Farmers usually grow this crop for their own use. The main commercial production area is in Hokkaido district (the northernmost island in Japan).
Japan imported 79,978 MT of azuki bean in 1994. More than 90% was imported from China (Zatsumame Yunyu Kikin Kyokai. 1995).
In Japan, azuki bean has been used for making "sekihan" (steamed glutinous rice colored red by boiled azuki or sasage bean,V.unguiculata) and/or "azuki-gayu" (rice porridge with azuki bean) for the traditional ceremony and celebration. It is also cooked as "ann" (azuki bean jam) and/or "shiruko" (sweet azuki soup with glutinous rice cake).
Azuki is considered to have been domesticated in China, Korea or Japan from its wild ancestral form, V.angularis var.nipponensis (Ohwi) Ohwi & Ohashi. Recently, the natural distribution of V.angularis var.nipponensis was proved to be wider than recognized before, ranging from Japan, Korea, China to Himalaya (Tateishi 1984, also see p.39, Fig.4.1. in Lumpkin and McClary 1994).
Therefore, the area of domestication should be reconsidered from these regions. This area is called the "Sino-Japanese Region" according to plant geography classification.
Azuki bean is an annual food legume belonging to the subgenus Ceratotropis in the genus Vigna. The genus Vigna, together with the closely related genus Phaseolus, forms a very complicated taxonomic group, so called Phaseolus-Vigna complex.
Verdcourt (1970) proposed a very restricted concept of Phaseolus, limiting it exclusively to those American species with a tightly coiled style and pollen grains lacking course reticulation, hence, promoting significantly the concept of Vigna.
According to his proposal, azuki bean, mungbean and its relatives (which is now recognized as the subgenus Ceratotropis) were transferred to the genus Vigna from the genus Phaseolus.
Marechal et al. (1978) followed Verdcourt and presented a monograph on the Phaseolus-Vigna complex. Their taxonomic system is generally accepted now. 2n=22.
Azuki bean has been cultivated in China, Korea and Japan. Usually, it shows an erect growth habit, however some azuki bean cultivated in Nepal and Bhutan shows twining form.
Flower color is pale yellow. Seed color is diverse, ranging from red, white, black, gray seed mottled with black ("called kage azuki in Japan") to white seed mottled with red ("called anego azuki in Japan"). Germination is hypogeal.
The dry seeds are boiled and used in various ways.
Hoshikawa,K. 1981. Azuki (Azuki bean). in "Shokuyou Sakumotu" (Food Crops). Yoken-do, Tokyo. (in Japanese) pp.460-470.
Lumpkin,T.A. and McClary,D.C. 1994. Azuki Bean : Botany, Production and Uses. CAB International.
Marechal,R., J.M.Mascherpa and F.Stainer. 1978. Etude taxonomique d'un groupe complexe d'speces des genres Phaseolus et Vigna (Papilionaceae) sur la base de donnees morphologiques et polliniques, traitees par l'analyse informatique. Boissiera 28.
Tateishi,Y. 1984. Contributions to the Genus Vigna (Leguminosae) in Taiwan I. Sci. Rep. Tohoku Univ. 4th ser. (Biology) 38: 335-350.
Verdcourt,B. 1970. Studies in the Leguminosae - Papilionoideae for the "Flora of Tropical East Africa" : IV. Kew Bulletin 24 : pp.558-560.
Zatsumame Yunyu Kikin Kyokai. 1995. Yunyu Mamerui Zukan (A pictorial book of imported food legumes) (in Japanese).