''Vigna angularis'', also known as the , azuki bean, aduki bean, red bean, or red mung bean, is an annual

vine A vine is any plant with a growth habit of trailing or scandent (that is, climbing) stems, lianas, or runners. The word ''vine'' can also refer to such stems or runners themselves, for instance, when used in wicker work.Jackson; Benjamin; Da ...

widely cultivated throughout

East Asia East Asia is a geocultural region of Asia. It includes China, Japan, Mongolia, North Korea, South Korea, and Taiwan, plus two special administrative regions of China, Hong Kong and Macau. The economies of Economy of China, China, Economy of Ja ...

for its small (approximately long)

bean A bean is the seed of some plants in the legume family (Fabaceae) used as a vegetable for human consumption or animal feed. The seeds are often preserved through drying (a ''pulse''), but fresh beans are also sold. Dried beans are traditi ...

. The

cultivar A cultivar is a kind of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and which retains those traits when Plant propagation, propagated. Methods used to propagate cultivars include division, root a ...

s most familiar in East Asia have a uniform red color, but there are white,

black Black is a color that results from the absence or complete absorption of visible light. It is an achromatic color, without chroma, like white and grey. It is often used symbolically or figuratively to represent darkness.Eva Heller, ''P ...

, gray, and variously mottled varieties. Scientists presume ''Vigna angularis'' var. ''nipponensis'' is the

progenitor In genealogy, a progenitor (rarer: primogenitor; or ''Ahnherr'') is the founder (sometimes one that is legendary) of a family, line of descent, gens, clan, tribe, noble house, or ethnic group.. Ebenda''Ahnherr:''"Stammvater eines Geschlec ...

Origin and diversity

Speciation and domestication

The wild ancestor of cultivated adzuki bean is probably ''Vigna angularis'' var. ''nipponensis'', which is distributed across East Asia.

Speciation Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within ...

between ''Vigna angularis'' var. ''nipponensis'' and ''Vigna angularis'' var. ''angularis'' occurred around years ago. Wild adzuki likely originated near the Himalayas and spread naturally to central China and Japan. Archaeologists estimate it was domesticated around 3000 BC. However, adzuki beans, as well as soybeans, dating from 3000 BC to 2000 BC are indicated to still be largely within the wild size range. Enlarged seeds occurred during the later

Bronze Age The Bronze Age () was a historical period characterised principally by the use of bronze tools and the development of complex urban societies, as well as the adoption of writing in some areas. The Bronze Age is the middle principal period of ...

Iron Age The Iron Age () is the final epoch of the three historical Metal Ages, after the Chalcolithic and Bronze Age. It has also been considered as the final age of the three-age division starting with prehistory (before recorded history) and progre ...

, periods with plough use.

Domestication Domestication is a multi-generational Mutualism (biology), mutualistic relationship in which an animal species, such as humans or leafcutter ants, takes over control and care of another species, such as sheep or fungi, to obtain from them a st ...

of adzuki beans resulted in a trade-off between yield and seed size. Cultivated adzuki beans have fewer but longer pods, fewer but larger seeds, a shorter stature, and also a smaller overall seed yield than wild forms. The exact place of domestication is not known; multiple domestication origins in East Asia have been suggested. Seed remains of adzuki beans discovered in the Central Highlands of Japan were dated to c. 6,000–4,000 BP, and represent to date the oldest evidence for its cultivation, supporting an origin in Japan. Evidence suggests that "wild azuki bean have been domesticated and cultivated in Japan for over 10,000 years". While archaeological studies found early traces of adzuki cultivation in Japan, genetic studies identified highest cultivar genetic variation in central China, suggesting the first domestication in China. Consistent with archaeological records, a genomic study indicated that all present-day adzuki cultivars descended from the wild adzuki in eastern Japan near the Central Highlands, at about 3000-5000 BP. The cultivars later spread to China and hybridized with local wild adzuki in China, resulting in the high genetic variation of central Chinese cultivars. The study therefore reconciles the discrepancy between archaeological and early genetic studies. Mutations conferring key domestication syndromes (loss of pod shattering and change of seed coat color) also had a single origin in Japan. These mutations originated and continued to increase in frequency since about 10,000 BP, suggesting that domestication syndromes were being selected by the Jōmon people much earlier than clear archaeological traces of large-scale cultivation.

Breeding

In Japan, the adzuki bean was one of the first crops subjected to scientific

plant breeding Plant breeding is the science of changing the traits of plants in order to produce desired characteristics. It is used to improve the quality of plant products for use by humans and animals. The goals of plant breeding are to produce crop varie ...

. Important breeding traits are yield, pureness of the bean colour, and the maturing time. Separate cultivars with smaller seeds and higher biomass are bred for

fodder Fodder (), also called provender (), is any agriculture, agricultural foodstuff used specifically to feed domesticated livestock, such as cattle, domestic rabbit, rabbits, sheep, horses, chickens and pigs. "Fodder" refers particularly to food ...

production and as

green manure In agriculture, a green manure is a crop specifically cultivated to be incorporated into the soil while still green. Typically, the green manure's Biomass (ecology), biomass is incorporated with a plow or disk, as is often done with (brown) man ...

. Locally adapted cultivars are available in China, Japan, Korea, and Taiwan. More than 300 cultivars/landraces/breeding lines are registered in Japan. Large

germplasm Germplasm refers to genetic resources such as seeds, tissues, and DNA sequences that are maintained for the purpose of animal and plant breeding, conservation efforts, agriculture, and other research uses. These resources may take the form of s ...

collections of adzuki bean are in China, at the Institute of Crop Germplasm Resources (CAAS),

Beijing Beijing, Chinese postal romanization, previously romanized as Peking, is the capital city of China. With more than 22 million residents, it is the world's List of national capitals by population, most populous national capital city as well as ...

, with more than 3,700 accessions, and Japan, at the Tokachi Agricultural Experiment Station,

Hokkaido is the list of islands of Japan by area, second-largest island of Japan and comprises the largest and northernmost prefectures of Japan, prefecture, making up its own list of regions of Japan, region. The Tsugaru Strait separates Hokkaidō fr ...

, with about 2,500 accessions.

Weed forms

Weed A weed is a plant considered undesirable in a particular situation, growing where it conflicts with human preferences, needs, or goals.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. Pla ...

forms of adzuki bean frequently occur in Japan. The wide spread of weed forms is due to adaptation to human-disturbed habitats, escapes of old

cultivars A cultivar is a kind of cultivated plant that people have selected for desired traits and which retains those traits when propagated. Methods used to propagate cultivars include division, root and stem cuttings, offsets, grafting, tissue cult ...

, and natural establishment from derivatives of hybrids between cultivars and wild forms. In contrast to wild forms, the weed forms of adzuki bean are used as a substitute for the cultivated form and consumed as sweet beans, especially if cultivated adzuki beans are attacked by pests. However, in cultivated gardens the weed form is recognized as contamination and lowers the seed quality of adzuki cultivars.

Names

The name ''adzuki'' is a transliteration of the Japanese , as it was spelled according to

historical kana orthography The , or , refers to the in general use until orthographic reforms after World War II; the current orthography was adopted by Cabinet order in 1946. By that point the historical orthography was no longer in accord with Japanese pronunciati ...

. The names ''azuki'' and ''aduki'' reflect the modern pronunciation (

hiragana is a Japanese language, Japanese syllabary, part of the Japanese writing system, along with ''katakana'' as well as ''kanji''. It is a phonetic lettering system. The word ''hiragana'' means "common" or "plain" kana (originally also "easy", ...

: ). All are meant to represent the same Modern Japanese pronunciation, ''azuki''. Japanese also has a Chinese

loanword A loanword (also a loan word, loan-word) is a word at least partly assimilated from one language (the donor language) into another language (the recipient or target language), through the process of borrowing. Borrowing is a metaphorical term t ...

, , which means "small bean", its counterpart being the

soybean The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume native to East Asia, widely grown for its edible bean. Soy is a staple crop, the world's most grown legume, and an important animal feed. Soy is a key source o ...

. It is common to write in

kanji are logographic Chinese characters, adapted from Chinese family of scripts, Chinese script, used in the writing of Japanese language, Japanese. They were made a major part of the Japanese writing system during the time of Old Japanese and are ...

but pronounce it as ''azuki'' ', an example of '. In China, the corresponding name ( zh, c=小豆, p=xiǎodòu) still is used in botanical or agricultural parlance. In everyday Chinese, the more common terms are ' ( zh, p=hóngdòu, labels=no, s=红豆, t=紅豆) and ' ( zh, c=赤豆, p=chìdòu, labels=no), both meaning "red bean", because almost all Chinese cultivars are uniformly red. In English the beans are often described as "red beans" in the context of Chinese cuisine, such as with

red bean paste Red bean paste () or red bean jam, also called adzuki bean paste or ''anko'' (a Japanese word), is a paste made of red beans (also called "adzuki beans"), used in East Asian cuisine. The paste is prepared by boiling the beans, then mashing or ...

. In Korean, adzuki beans are called ' () and it contrasts with ' (, "bean"), rather than being considered a type of it. ' ("beans") without qualifiers usually means

s. In Vietnamese it is called ' (literally: red bean). In some parts of India, the beans are referred to as "red chori". In Marathi, it is known as ' (), literally meaning 'red

cowpea The cowpea (''Vigna unguiculata'') is an annual herbaceous legume from the genus '' Vigna''. Its tolerance for sandy soil and low rainfall have made it an important crop in the semiarid regions across Africa and Asia. It requires very few inpu ...

'. In Iraq its name is ' () meaning "red cowpeas".

Cultivation

Area and yield

The adzuki bean is mainly cultivated in China (), Japan (), South Korea (), and Taiwan () (data published 2006). The bean is also grown commercially in the US, South America, India, New Zealand, Congo, and Angola. In Japan, the adzuki bean is the second most important

legume Legumes are plants in the pea family Fabaceae (or Leguminosae), or the fruit or seeds of such plants. When used as a dry grain for human consumption, the seeds are also called pulses. Legumes are grown agriculturally, primarily for human consum ...

after the soy bean. In 1998, the annual crop yield was around . In 2006, Japan consumed about /year. Japan is the largest importer of adzuki beans. The imports come from China, Korea, Colombia, Taiwan, US, Thailand, and Canada.

Ecological requirements

Optimal temperature range for adzuki bean growth is between . The crop is not frost-hardy and needs soil temperatures above ( optimal) for

germination Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, ...

. Hot temperatures stimulate vegetative growth and are therefore less favorable for pea production. The adzuki bean is usually not irrigated. Annual rainfall ranges from in areas where the bean is grown. The plant can withstand

drought A drought is a period of drier-than-normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, ...

but severe reduction in yield is expected. The cultivation of the adzuki bean is possible on preferably well drained soils with pH 5–7.5. Fertilizer application differs widely depending on expected yield but is generally similar to soybean. Due to nodulation with

rhizobia Rhizobia are diazotrophic bacteria that fix nitrogen after becoming established inside the root nodules of legumes (Fabaceae). To express genes for nitrogen fixation, rhizobia require a plant host; they cannot independently fix nitrogen. I ...

nitrogen fixation Nitrogen fixation is a chemical process by which molecular dinitrogen () is converted into ammonia (). It occurs both biologically and abiological nitrogen fixation, abiologically in chemical industry, chemical industries. Biological nitrogen ...

of up to is possible.

Production

The sowing of the peas is in depth in rows apart and within the row. Rarely seeds are sown by broadcast. The amount of seeds ranges between . Growth of the crop is slow, therefore

weed control Weed control is a type of pest control, which attempts to stop or reduce growth of weeds, especially noxious weeds, with the aim of reducing their competition with desired flora and fauna including domesticated plants and livestock, and in natu ...

is crucial mainly between germination and flowering. Cultivation systems differ largely among different countries. In China adzuki bean is often grown in intercrops with maize, sorghum and millet while in Japan the bean is grown in

crop rotation Crop rotation is the practice of growing a series of different types of crops in the same area across a sequence of growing seasons. This practice reduces the reliance of crops on one set of nutrients, pest and weed pressure, along with the pro ...

s. Harvest of the peas should not be done as long as moisture content of the seed is higher than 16%.

Pests and diseases

Fungal and bacterial diseases of the adzuki bean are

powdery mildew Powdery mildew is a fungus, fungal disease that affects a wide range of plants. Powdery mildew diseases are caused by many different species of Ascomycota, ascomycete fungi in the order Erysiphales. Powdery mildew is one of the easier plant disea ...

, brown stem rot, and bacterial

blight Blight is a specific symptom affecting plants in response to infection by a pathogenic organism. Description Blight is a rapid and complete chlorosis, browning, then death of plant tissues such as leaves, branches, twigs, or floral organs. A ...

. Furthermore, pests such as the adzuki pod worm, Japanese butterbur borer, and

cutworm Cutworms are moth larvae that hide under litter or soil during the day, coming out in the dark to feed on plants. A larva typically attacks the first part of the plant it encounters, namely the stem, often of a seedling, and consequently cuts it ...

attack the crop. The

bean weevil The bean weevils or seed beetles are a subfamily (Bruchinae) of weevils, which in turn are a subset of beetles. The Bruchinae now placed in the family Chrysomelidae, though they have historically been treated as a separate family. The subfamily ...

is an important storage pest.

Botany

The description of the adzuki bean can vary between authors because there are both wild and cultivated forms of the plant. The adzuki bean is an annual, rarely biennial bushy erect or twining herb usually between high. There exist climbing or prostrate forms of the plant. The stem is normally green and sparsely pilose.

Roots

The adzuki bean has a

taproot A taproot is a large, central, and dominant root from which other roots sprout laterally. Typically a taproot is somewhat straight and very thick, is tapering in shape, and grows directly downward. In some plants, such as the carrot, the taproot ...

type of root system that can reach a depth of from the point of seed germination.

Leaves

The leaves of the adzuki bean are

trifoliate The following terms are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (that is, the leaf blade or 'lamina' is undivided) or compound (that is, the leaf blade is divided into two or more leaflets ...

pinnate Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, and ...

and arranged alternately along the stem on a long petiole. Leaflets are ovate and about long and wide.

Flowers

Adzuki flowers are

papilionaceous Papilionaceous flowers (from Latin: ''papilion'', a butterfly) are flowers with the characteristic irregular and butterfly-like corolla found in many, though not all, plants of the species-rich Faboideae subfamily of legumes. Tournefort sugge ...

and bright yellow. The

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

is an axillary false

raceme A raceme () or racemoid is an unbranched, indeterminate growth, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are ...

consisting of six to ten (two to twenty) flowers.

Fruits

Adzuki pods are smooth, cylindrical and thin-walled. The colour of the pods is green turning white to grey as they mature. The size is between with 2 to 14 seeds per pod. Pod shatter during seed ripening and harvesting might be a difficulty under certain conditions.

Seeds

The seeds are smooth and subcylindric with a length of , width of , thickness of . The thousand kernel weight is between 50 and 200 g. There are many different seed colours from maroon to blue-black mottled with straw.

Physiology

The emergence of the seedlings is hypogeal and takes 7–20 days. Compared to other pulses the growth of the plant is slow. Normally the adzuki plant reaches maturity between 80 and 120 days depending on the cultivar and the environmental conditions.

Flowering Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...

lasts 30–40 days. Commonly the plant self-pollinates but cross-pollination also exists.

Culinary uses

East Asian cuisine This is a list of Asian cuisines, by region. A cuisine is a characteristic style of cooking practices and traditions, usually associated with a specific culture or region. Asia, being the largest, most populous and culturally diverse continent, ...

, the adzuki bean is commonly sweetened before eating. In particular, it is often boiled with sugar, producing red bean paste, a very common ingredient in all of these cuisines. It is common to add flavoring to the bean paste, such as chestnut. Red bean paste is used in many Chinese dishes, such as tangyuan,

zongzi ''Zongzi'' () or simply ''zong'' () is a traditional Chinese rice dish made of glutinous rice stuffed with a range of fillings and wrapped in bamboo leaves. Fillings can be either sweet, such as red bean paste, or savory, such as pork belly or ...

mooncake A mooncake () is a Chinese bakery product traditionally eaten during the Mid-Autumn Festival (中秋節). The festival is primarily about the harvest while a legend connects it to moon watching, and mooncakes are regarded as a delicacy. ...

baozi Baozi (), or simply bao, is a type of yeast-leavened filled bun in various Chinese cuisines. There are many variations in fillings (meat or vegetarian) and preparations, though the buns are most often steaming, steamed. They are a variation of ...

, and red bean ice. It serves as a filling in

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

ese sweets such as anpan, dorayaki, imagawayaki, manjū, monaka, anmitsu, taiyaki, and daifuku. A more liquid version, using adzuki beans boiled with sugar and a pinch of salt, produces a sweet dish called hong dou tang. Some East Asian cultures enjoy red bean paste as a filling or topping for various kinds of waffles, pastries, baked buns, or biscuits. Adzuki beans are commonly eaten sprouted or boiled in a hot,

tea Tea is an aromatic beverage prepared by pouring hot or boiling water over cured or fresh leaves of '' Camellia sinensis'', an evergreen shrub native to East Asia which probably originated in the borderlands of south-western China and nor ...

-like drink. Traditionally in Japan, rice with adzuki beans ( 赤飯; ''

sekihan Red bean rice, called ''patbap'' () in Korean language, Korean, ''sekihan'' () in Japanese language, Japanese, and ''hóngdòu fàn'' () in Chinese language, Chinese, is an East Asian rice dish consisting of cooked rice, rice cooked with adzuki ...

'') is cooked for auspicious occasions. Adzuki beans are used in amanattō and

ice cream Ice cream is a frozen dessert typically made from milk or cream that has been flavoured with a sweetener, either sugar or an alternative, and a spice, such as Chocolate, cocoa or vanilla, or with fruit, such as strawberries or peaches. Food ...

with the whole bean or as paste.

Nutritional information

Cooked adzuki beans are 66% water, 25%

carbohydrates A carbohydrate () is a biomolecule composed of carbon (C), hydrogen (H), and oxygen (O) atoms. The typical hydrogen-to-oxygen atomic ratio is 2:1, analogous to that of water, and is represented by the empirical formula (where ''m'' and ''n'' ma ...

, including 7%

dietary fiber Dietary fiber (fibre in English in the Commonwealth of Nations, Commonwealth English) or roughage is the portion of plant-derived food that cannot be completely broken down by human digestive enzymes. Dietary fibers are diverse in chemical co ...

, 8%

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

, and contain negligible

fat In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food. The term often refers specif ...

(table). In a 100-gram reference amount, cooked beans provide of

food energy Food energy is chemical energy that animals and humans derive from food to sustain their metabolism and muscular activity. Most animals derive most of their energy from aerobic respiration, namely combining the carbohydrates, fats, and protein ...

, a moderate to high content (10% or more of the

Daily Value In the U.S. and Canada, the Reference Daily Intake (RDI) is used in nutrition labeling on food and dietary supplement products to indicate the daily intake level of a nutrient that is considered to be sufficient to meet the requirements of 97� ...

, DV) of the B vitamin

folate Folate, also known as vitamin B9 and folacin, is one of the B vitamins. Manufactured folic acid, which is converted into folate by the body, is used as a dietary supplement and in food fortification as it is more stable during processing and ...

(30% DV), and several

dietary minerals In the context of nutrition, a mineral is a chemical element. Some "minerals" are essential for life, but most are not. ''Minerals'' are one of the four groups of essential nutrients; the others are vitamins, essential fatty acids, and essen ...

(11% to 27% DV, table).

Gallery

File:Red bean paste anko.JPG,

Red bean paste Red bean paste () or red bean jam, also called adzuki bean paste or ''anko'' (a Japanese word), is a paste made of red beans (also called "adzuki beans"), used in East Asian cuisine. The paste is prepared by boiling the beans, then mashing or ...

File:Azuki bean ice cream.jpg, Azuki bean

HK 旺角 Mong kok 朗豪坊 Langham Place 香港康得思酒店 Cordis Hotel buffet food November 2018 SSG Red bean sugar soup n sesame ball.jpg, Chinese '' hong dou tang'' File:HK food 缽仔糕 Put chai ko 紅豆砵仔糕 Steamed Red Bean Rice Pudding cakes May 2017 IX1 04.jpg, Chinese '' put chai ko'' File:Korean shaved ice-Patbingsu-10B.jpg, Korean '' patbingsu'' File:Sirutteok.jpg, Korea '' sirutteok'' File:Dorayaki 004.jpg, Japanese '' dorayaki'' File:Botamochi 001.jpg, Japanese '' botamochi''

References

External links

Illustrated Plant Genetic Resources Database

* {{DEFAULTSORT:Adzuki Bean Articles containing video clips Edible legumes Japanese cuisine Korean cuisine Vigna Yunnan cuisine