Editing Soybean (section)

==Description==
{{More citations needed section|date=July 2021}}

Like most plants, soybeans grow in distinct [[Plant morphology|morphological]] stages as they develop from seeds into fully mature plants.

===Germination===
The first stage of growth is [[germination]], a method which first becomes apparent as a seed's [[radicle]] emerges.<ref name=MP197Chapter2>{{cite book |last1=Purcell |first1=Larry C. |last2=Salmeron |first2=Montserrat |last3=Ashlock |first3=Lanny |title=Arkansas Soybean Production Handbook – MP197 |date=2014 |chapter=Chapter 2 |chapter-url=http://www.uaex.edu/publications/pdf/mp197/chapter2.pdf |publisher=University of Arkansas Cooperative Extension Service|location=Little Rock|pages=1–8 |url=http://www.uaex.edu/publications/mp-197.aspx |access-date=21 February 2016 |archive-date=March 4, 2016 |archive-url=https://web.archive.org/web/20160304011452/http://www.uaex.edu/publications/mp-197.aspx }}</ref> This is the first stage of root growth and occurs within the first 48 hours under ideal growing conditions. The first [[photosynthesis|photosynthetic]] structures, the [[cotyledon]]s, develop from the [[hypocotyl]], the first plant structure to emerge from the soil. These cotyledons both act as leaves and as a source of nutrients for the immature plant, providing the seedling nutrition for its first 7 to 10 days.<ref name=MP197Chapter2 />

[[File:Glycine max 003.JPG|thumb|Fruits/pods]]

===Maturation===
The first true leaves develop as a pair of [[Leaf#Divisions of the blade|single blades]].<ref name=MP197Chapter2 /> Subsequent to this first pair, mature [[Plant stem|nodes]] form compound leaves with three blades. Mature [[trifoliolate]] leaves, having three to four [[leaflet (botany)|leaflets]] per leaf, are often between {{convert|6|and|15|cm|in|frac=2|abbr=on}} long and {{convert|2|and|7|cm|in|frac=2|abbr=on}} broad. Under ideal conditions, stem growth continues, producing new nodes every four days. Before flowering, roots can grow {{convert|2|cm|in|frac=8|abbr=on}} per day. If [[rhizobia]] are present, [[root nodule|root nodulation]] begins by the time the third node appears. Nodulation typically continues for 8 weeks before the [[Rhizobia#Infection and signal exchange|symbiotic infection]] process stabilizes.<ref name=MP197Chapter2 /> The final characteristics of a soybean plant are variable, with factors such as genetics, [[soil quality]], and climate affecting its form; however, fully mature soybean plants are generally between {{convert|50|and|125|cm|in|-1|abbr=on}} in height<ref name=MP197Chapter19>{{cite book |last1=Purcell |first1=Larry C. |last2=Salmeron |first2=Montserrat |last3=Ashlock |first3=Lanny |title=Arkansas Soybean Production Handbook – MP197 |date=2000 |chapter=Chapter 19: Soybean Facts |chapter-url=http://www.uaex.edu/publications/pdf/mp197/chapter19.pdf |publisher=University of Arkansas Cooperative Extension Service |location=Little Rock, AR |page=1 |url=http://www.uaex.edu/publications/mp-197.aspx |access-date=5 September 2016 |archive-date=March 4, 2016 |archive-url=https://web.archive.org/web/20160304011452/http://www.uaex.edu/publications/mp-197.aspx }}</ref> and have rooting depths between {{convert|75|and|150|cm|in|-1|abbr=on}}.<ref>{{cite book |last1=Bennett |first1=J. Michael |last2=Rhetoric |first2=Emeritus |last3=Hicks |first3=Dale R. |last4=Naeve |first4=Seth L. |last5=Bennett |first5=Nancy Bush |title=The Minnesota Soybean Field Book |date=2014 |publisher=[[University of Minnesota Extension]]|location=St Paul, MN |page=33 |url=http://www.extension.umn.edu/agriculture/soybean/docs/minnesota-soybean-field-book.pdf |access-date=16 September 2016 |archive-url=https://web.archive.org/web/20130930151502/http://www1.extension.umn.edu/agriculture/soybean/docs/minnesota-soybean-field-book.pdf |archive-date=September 30, 2013  }}</ref>

===Flowering===
Flowering is [[Photoperiodism|triggered by day length]], often beginning once days become shorter than 12.8 hours.<ref name=MP197Chapter2 /> This trait is highly variable however, with different [[Variety (botany)|varieties]] reacting differently to changing day length.<ref>{{cite book |last1=Shurtleff |first1=William |author-link=William Shurtleff |last2=Aoyagi |first2=Akiko |author-link2=Akiko Aoyagi |title=History of Soybeans and Soyfoods in Sweden, Norway, Denmark and Finland (1735–2015): Extensively Annotated Bibliography and Sourcebook |date=2015 |publisher=Soyinfo Center|location=Lafayette|isbn=978-1-928914-80-8 |page=490 |url=https://books.google.com/books?id=0gtpCgAAQBAJ&pg=PA490}}</ref> Soybeans form inconspicuous, self-fertile flowers which are borne in the [[axil]] of the leaf and are white, pink or purple. Though they do not require pollination, they are attractive to bees, because they produce nectar that is high in sugar content.<ref>{{Cite web |last=Reisig |first=Dominic |title=Soybean flowering, pollination, and bees |url=http://www.ncagr.gov/pollinators/documents/DominicReisig-NCPollinatorProtectionSoybeans.pdf |website=[[North Carolina Department of Agriculture & Consumer Services]] |access-date=July 15, 2021 |archive-date=June 28, 2021 |archive-url=https://web.archive.org/web/20210628160525/http://www.ncagr.gov/pollinators/documents/DominicReisig-NCPollinatorProtectionSoybeans.pdf |url-status=dead }}</ref> Depending on the soybean variety, node growth may cease once flowering begins. Strains that continue nodal development after flowering are termed "[[Indeterminate growth|indeterminates]]" and are best suited to climates with longer growing seasons.<ref name=MP197Chapter2 /> Often soybeans drop their leaves before the seeds are fully mature.

[[File:Soybean flowers.png|thumb|Small, purple flowers]]

The fruit is a hairy pod that grows in clusters of three to five, each pod is {{convert|3|–|8|cm|in|frac=2|abbr=on}} long and usually contains two to four (rarely more) [[seed]]s 5–11&nbsp;mm in diameter. Soybean seeds come in a wide variety of sizes and [[husk|hull]] colors such as black, brown, yellow, and green.<ref name=MP197Chapter19 /> Variegated and bicolored seed coats are also common.

===Seed resilience===
[[File:Soybeanvarieties.jpg|thumb|Bean varieties]]

The hull of the mature bean is hard, water-resistant, and protects the [[cotyledon]] and [[hypocotyl]] (or "germ") from damage. If the seed coat is cracked, the seed will not [[germinate]]. The scar, visible on the seed coat, is called the [[Hilum (biology)|hilum]] (colors include black, brown, buff, gray and yellow) and at one end of the hilum is the [[Micropyle (botany)|micropyle]], or small opening in the seed coat which can allow the absorption of water for sprouting.

Some seeds such as soybeans containing very high levels of [[soy protein|protein]] can undergo [[desiccation]], yet survive and revive after water absorption. [[A. Carl Leopold]] began studying this capability at the [[Boyce Thompson Institute for Plant Research]] at [[Cornell University]] in the mid-1980s. He found soybeans and corn to have a range of soluble [[carbohydrate]]s protecting the seed's cell viability.<ref>{{cite journal |pages=225–30 |doi=10.1104/pp.100.1.225 |title=Maturation Proteins and Sugars in Desiccation Tolerance of Developing Soybean Seeds |year=1992 |last1=Blackman |first1=S.A. |last2=Obendorf |first2=R.L. |last3=Leopold |first3=A.C. |journal=[[Plant Physiology (journal)|Plant Physiology]] |volume=100 |pmid=16652951 |issue=1 |pmc=1075542}}</ref> Patents were awarded to him in the early 1990s on techniques for protecting biological membranes and proteins in the dry state.

=== Chemistry ===
Dry soybeans contain 36% [[protein]] and 20% [[fat]] in form of [[soybean oil]] by weight. The remainder consists of 30% [[carbohydrate]]s, 9% water and 5% [[Ash (analytical chemistry)|ash]].<ref>See ''[[#Nutrition|Nutrition]]'' table</ref> 
Soybeans comprise approximately 8% seed coat or hull, 90% [[cotyledon]]s and 2% [[hypocotyl]] axis or germ.<ref>{{Cite book |title=Encyclopedia of Grain Science |last=Corke, Walker and Wrigley |publisher=[[Academic Press]] |year=2004 |isbn=978-0-12-765490-4}}</ref>{{Page needed|date=November 2015}}