Editing Adzuki bean

{{Short description|East and south Asian crop}}

| image_caption = Also called "red mung beans"

''Vigna angularis'', also known as the '''adzuki bean''' {{nihongo||{{linktext|小豆}} (アズキ)||''azuki'', {{lang|en|Uncommon}} アヅキ, ''adzuki''|lead=yes}}, '''azuki bean''', '''aduki bean''', '''red bean''', or '''red mung bean''', is an [[Annual plant|annual]] [[vine]] widely cultivated throughout [[East Asia]] for its small (approximately {{Convert|5|mm|in|frac=8|abbr=on|disp=or}} long) [[bean]]. The [[cultivar]]s most familiar in East Asia have a uniform red color, but there are also white, [[Black adzuki bean|black]], gray, and variously [[mottle]]d varieties.

Scientists presume ''Vigna angularis'' var. ''nipponensis'' is the [[progenitor]].<ref>{{cite journal|pmc=4629392|year=2015|last1=Yang|first1=K|title=Genome sequencing of adzuki bean (''Vigna angularis'') provides insight into high starch and low fat accumulation and domestication|journal= [[Proceedings of the National Academy of Sciences]] |volume=112|issue=43|pages=13213–13218|last2=Tian|first2=Z|last3=Chen|first3=C|last4=Luo|first4=L|last5=Zhao|first5=B|last6=Wang|first6=Z|last7=Yu|first7=L|last8=Li|first8=Y|last9=Sun|first9=Y|last10=Li|first10=W|last11=Chen|first11=Y|last12=Li|first12=Y|last13=Zhang|first13=Y|last14=Ai|first14=D|last15=Zhao|first15=J|last16=Shang|first16=C|last17=Ma|first17=Y|last18=Wu|first18=B|last19=Wang|first19=M|last20=Gao|first20=L|last21=Sun|first21=D|last22=Zhang|first22=P|last23=Guo|first23=F|last24=Wang|first24=W|last25=Li|first25=Y|last26=Wang|first26=J|last27=Varshney|first27=R. K|last28=Wang|first28=J|last29=Ling|first29=H. Q|last30=Wan|first30=P|pmid=26460024|doi=10.1073/pnas.1420949112|bibcode=2015PNAS..11213213Y|doi-access=free}}</ref>

The wild ancestor of cultivated adzuki bean is probably ''Vigna angularis'' var. ''nipponensis'',<ref name="Yamaguchi">{{cite journal |last=Yamaguchi |first=Hirofumi |date=1992 |title=Wild and Weed Azuki Beans in Japan |journal= [[Economic Botany]] |volume=46 |issue=4 |pages=384–394 |doi=10.1007/bf02866509|s2cid=22975059 }}</ref> which is distributed across East Asia.<ref name="Kaga"/> [[Speciation]] between ''Vigna angularis'' var. ''nipponensis'' and ''Vigna angularis'' var. ''angularis'' occurred around {{formatnum:50000}} years ago.<ref name="Kang">{{cite journal |last=Kang |first=Yang Jae |date=2015 |title=Draft sequence of adzuki bean, ''Vigna angularis'' |journal= Scientific Reports |volume=5 |issue=8069 |pages=8069 |doi=10.1038/srep08069 |pmid=25626881 |pmc=5389050 }}</ref> Archaeologists estimate it was domesticated around 3000 BC.<ref name="Lee">{{cite journal |last=Lee |first=Gyoung-Ah |date=2012 |title=Archaeological perspectives on the origins of azuki (''Vigna angularis'') |journal= [[The Holocene]] |volume=23 |issue=3 |pages=453–459 |doi=10.1177/0959683612460788|s2cid=130903554 }}</ref> 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]] or [[Iron Age]], periods with plough use.<ref name="Fuller">{{cite journal |last= Fuller|first=Dorian Q|date=2007 |title=Contrasting Patterns in Crop Domestication and Domestication Rates: Recent Archaeobotanical Insights from the Old World |journal= [[Annals of Botany]] |volume=100 |issue=5|pages= 903–924|doi=10.1093/aob/mcm048|pmid=17495986|pmc=2759199}}</ref> [[Domestication]] 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.<ref name="Kaga"/> The exact place of domestication is not known;<ref name="Yamaguchi"/> multiple domestication origins in East Asia have been suggested.<ref name="Lee"/>

Seed remains of Adzuki beans discovered at the Central Highlands of Japan were dated to c. 6,000–4,000 BP, and represent the to date 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".<ref>{{Cite journal |last1=Takahashi |first1=Yu |last2=Nasu |first2=Hiroo |last3=Nakayama |first3=Seiji |last4=Tomooka |first4=Norihiko |date=2023 |title=Domestication of azuki bean and soybean in Japan: From the insight of archeological and molecular evidence |url=https://www.jstage.jst.go.jp/article/jsbbs/73/2/73_22074/_html/-char/en |journal=Breeding Science |volume=73 |issue=2 |pages=117–131 |doi=10.1270/jsbbs.22074|pmid=37404345 |pmc=10316305 }}</ref>

[[File:Leiden University Library - Seikei Zusetsu vol. 18, page 018 - 竹小豆 - Vigna umbellata (Thunb.) Ohwi & H.Ohashi, 1804.jpg|thumb|''[[Seikei Zusetsu]]'' (1804)]]

In Japan, the adzuki bean was one of the first crops subjected to scientific [[plant breeding]].<ref name="Kaga">{{cite journal |last1=Kaga |first1=Akito |last2=Isemura |first2=Takehisa |last3=Tomooka |first3=Norihiko |last4=Vaughan |first4=Duncan A. |date=2008 |title=The Genetics of Domestication of the Azuki Bean (Vigna angularis) |journal= [[Genetics (journal)|Genetics]] |volume=178 |issue=2 |pages=1013–1036 |doi=10.1534/genetics.107.078451|pmid=18245368 |pmc=2248364 }}</ref> Important breeding traits are yield, pureness of the bean colour, and the maturing time.<ref name="Schuster"/> Separate cultivars with smaller seeds and higher biomass are bred for [[fodder]] production and as [[green manure]].<ref name="Schuster"/> Locally adapted cultivars are available in China, Japan, Korea, and Taiwan.<ref name="Jansen"/> More than 300 cultivars/landraces/breeding lines are registered in Japan.<ref name="Jansen"/> Moreover, China (Institute of Crop Germplasm Resources (CAAS), [[Beijing]], more than 3700 accessions) and Japan (Tokachi Agricultural Experiment Station, [[Hokkaido]], about 2500 accessions) accommodate large [[germplasm]] collections of adzuki bean.<ref name="Jansen"/>

Japanese also has a Chinese [[loanword]], {{nihongo||小豆|shōzu}}, which means "small bean", its counterpart {{nihongo|"large bean"|大豆|''daizu''}} being the [[soybean]]. It is common to write {{lang|ja|小豆}} in [[kanji]] but pronounce it as ''azuki'' ''{{Audio|Ja-Adzuki.oga|listen}}'', an example of ''{{lang|ja-Latn|[[jukujikun]]}}''. In China, the corresponding name ({{zh|c=小豆|p=xiǎodòu}}) still is used in botanical or agricultural parlance, however, in everyday Chinese, the more common terms are ''{{lang|zh-Latn|hongdou}}'' ({{zh|c=红豆|p=hóngdòu|labels=no}}) and ''{{lang|zh-Latn|chidou}}'' ({{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]]. In Korean, adzuki beans are called ''{{lang|ko-Latn|pat}}'' ({{lang|ko|팥}}) and it contrasts with ''{{lang|ko-Latn|kong}}'' ({{lang|ko|콩}}, "bean"), rather than being considered a type of it. ''{{lang|ko-Latn|Kong}}'' ("beans") without qualifiers usually means [[soybean]]s. In Vietnamese it is called ''{{lang|vi|đậu đỏ}}'' (literally: red bean). In some parts of India, the beans are referred to as "red chori".<ref name="seedsofindia.com">{{cite web |url=http://www.seedsofindia.com/Beans.htm |title=Indian beans |publisher=Seedsofindia.com |access-date=2011-08-25 |archive-url=https://web.archive.org/web/20110720082405/http://www.seedsofindia.com/Beans.htm |archive-date=20 July 2011 |url-status=dead }}</ref> In [[Punjabi language|Punjabi]] it is called ''{{lang|pa-Latn|rajma}}'' and is a common ingredient of [[chaat]]. In [[Marathi language|Marathi]], it is known as ''{{lang|mr-Latn|lal chavali}}'' ({{lang|mr|लाल चवळी}}), literally meaning 'red [[cowpea]]'. In Iraq its name is ''{{lang|acm-Latn|lūbyā ḥamrāˈ}}'' ({{lang|acm|لوبيا حمراء}}) meaning "red cowpeas".

The adzuki bean is mainly cultivated in China ({{ Convert | 670000 |ha }}), Japan ({{ Convert | 60000 |ha }}), South Korea ({{ Convert | 25000 |ha }}), and Taiwan ({{ Convert | 15000 |ha }}) (data published 2006).<ref name="Jansen"/> The bean is also grown commercially in the US, South America, and India,<ref name="Floridata">{{cite web|url=http://floridata.com/Plants/Fabaceae/Vigna%20angularis/1225 |title=Floridata Plant Encyclopedia Vigna Angularis |publisher=Steve Christman |access-date=2016-11-08}}</ref> as well as New Zealand, Congo, and Angola.<ref name="Schuster" /> In Japan, the adzuki bean is the second most important [[legume]] after the [[soy bean]]; its 1998 annual yield of this crop was around {{ Convert | 100,000 | t }}.<ref name="Schuster"/> With a consumption of about {{ Convert | 140,000 |t }}/year (data published 2006), Japan is also the most important importer of adzuki beans.<ref name="Jansen"/> The imports are received from China, Korea, Colombia, Taiwan, US, Thailand, and Canada.<ref name="Schuster"/><ref name="Jansen"/>

Optimal temperature range for adzuki bean growth is between {{ Convert | 15 and 30 | C }}. The crop is not frost-hardy and needs soil temperatures above {{ Convert | 6–10 | C }} ({{ Convert | 30–34 | C }} optimal) for [[germination]]. Hot temperatures stimulate vegetative growth and are therefore less favorable for pea production.<ref name="Schuster">{{Cite web|url=http://geb.uni-giessen.de/geb/volltexte/2000/320/original/adzukibo.htm#TopOfPage|title=Adzukibohne (''Vigna angularis'' [Willd.] Ohwi et Ohashi)|last=Schuster|website=geb.uni-giessen.de|access-date=2016-11-03}}</ref><ref name="Jansen">{{Cite web|url= http://uses.plantnet-project.org/en/Vigna_angularis_%28PROTA%29|title=Vigna angularis (Willd.) Ohwi|last=Jansen |website=www.prota4u.org|access-date=2016-11-03}}</ref><ref name="Floridata"/> The adzuki bean is usually not irrigated. Annual rainfall ranges from {{ Convert | 500 to 1750 | mm }} in areas where the bean is grown. The plant can withstand [[drought]] but severe reduction in yield is expected.<ref name="Schuster" /><ref name="Jansen" /> The cultivation of the adzuki bean is possible on preferably well drained soils with pH 5–7.5.<ref name="Jansen" /><ref name="Floridata" /> Fertilizer application differs widely depending on expected yield but is generally similar to soybean. Due to nodulation with [[rhizobia]], [[nitrogen fixation]] of up to {{ Convert | 100 | kg/ha }} is possible.<ref name="Jansen" /><ref name="Floridata" />

The sowing of the peas is in {{ Convert | 2–3 | cm }} depth in rows {{ Convert | 30–90 | cm }} apart and {{ Convert |10–45 | cm }} within the row. Rarely seeds are sown by broadcast. The amount of seeds ranges between {{ Convert | 8–70 | kg/ha }}. Growth of the crop is slow, therefore [[weed control]] 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]]s. Harvest of the peas should not be done as long as moisture content of the seed is higher than 16%.<ref name="Jansen" />

[[File:Naturalis Biodiversity Center - RMNH.ART.651 - Vigna angularis - Kawahara Keiga - 1823 - 1829 - Siebold Collection - pencil drawing - water colour.jpeg|thumb|right| [[historical kana orthography|Historical kana]] アヅキ |alt=Illustration with [[historical kana orthography|historical kana]] アヅキ]]

The description of the adzuki bean can vary between authors because there are both wild<ref name="Efloras">{{Cite web|url= http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=242354363|title= ''Vigna''.: ''Vigna angularis'' (Willdenow) Ohwi & H. Ohashi |last1=Wu| first1=Delin|last2= Thulin|first2=Mats |access-date= 2016-11-09 }}</ref> and cultivated forms<ref name="Schuster"/> of the plant.

The adzuki bean is an [[annual plant|annual]],<ref name="Jansen"/><ref name="Efloras"/> rarely [[biennial plant|biennial]]<ref name="Schuster"/> bushy erect or twining herb<ref name="Jansen"/><ref name="Efloras"/> usually between {{ Convert |30 and 90 | cm }} high.<ref name="Efloras"/><ref name="Ecoport">{{Cite web|url=http://ecoport.org/ep?Plant=2147&entityType=PL****&entityDisplayCategory=full |title=Vigna angularis|last=FAO|access-date= 2016-11-09}}</ref> There exist climbing or prostrate forms of the plant.<ref name="Jansen"/> The stem is normally green<ref name="Ecoport"/> and sparsely [[pilose]].<ref name="Efloras"/>

The adzuki bean has a [[taproot]] type of root system that can reach a depth of {{ Convert | 40–50 | cm }} from the point of seed germination.<ref name="Ecoport"/><ref name="Lumpkin">{{Cite web|url= https://hort.purdue.edu/newcrop/proceedings1993/V2-045.html#AZUKI%20BEAN |title= Potential New Specialty Crops from Asia: Azuki Bean, Edamame Soybean, and Astragalus |last1=Lumpkin |first1=T.A. |last2=Konovsky |first2= J.C. |last3=Larson |first3=K.J. |last4=McClary |first4=D.C. |access-date= 2016-11-09 }}</ref>

The leaves of the adzuki bean are [[trifoliate]], [[pinnate]] and arranged alternately along the stem on a long [[petiole (botany)|petiole]].<ref name="Schuster"/><ref name="Jansen"/><ref name="Ecoport"/> Leaflets are ovate and about {{ Convert | 5–10 | cm }} long and {{ Convert | 5–8 | cm }} wide.<ref name="Schuster"/><ref name="Ecoport"/><ref name="Lumpkin"/>

Adzuki pods are smooth, cylindrical and thin-walled.<ref name="Ecoport"/><ref name="Lumpkin"/> The colour of the pods is green turning white to grey as they mature.<ref name="Ecoport"/><ref name="Lumpkin"/> The size is between {{ Convert | 5–13 × 0.5 | cm }} with 2 to 14 seeds per pod.<ref name="Jansen"/><ref name="Lumpkin"/> [[Shattering (agriculture)|Pod shatter]] during seed ripening and harvesting might be a difficulty under certain conditions.<ref name="Ecoport"/><ref name="Lumpkin"/>

The seeds are smooth and subcylindric with a length of {{ Convert | 5.0-9.1 | mm }}, width of {{ Convert | 4.0-6.3 | mm }}, thickness of {{ Convert | 4.1-6.0 | mm }}.<ref name="Ecoport"/><ref name="Lumpkin"/> The thousand kernel weight is between 50 and 200 g.<ref name="Schuster"/> There are many different seed colours from maroon to blue-black mottled with straw.<ref name="Fuller"/>

| note= [https://fdc.nal.usda.gov/fdc-app.html#/?query=Adzuki&format=full USDA Database entry]

In [[East Asian cuisine]], 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 also is common to add flavoring to the bean paste, such as chestnut. Red bean paste is used in many [[Chinese cuisine|Chinese dishes]], such as [[tangyuan (food)|tangyuan]], [[zongzi]], [[mooncake]]s, [[baozi]], and [[red bean ice]]. It also serves as a filling in [[Japan]]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.