Glycine max, soybean, soya bean, soja bean, Manchurian bean

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Taxonomy

cellular organisms - Eukaryota - Viridiplantae - Streptophyta - Streptophytina - Embryophyta - Tracheophyta - Euphyllophyta - Spermatophyta - Magnoliophyta - eudicotyledons - core eudicotyledons - rosids - eurosids I - Fabales - Fabaceae - Papilionoideae - Phaseoleae - Glycine - Glycine max

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Brief facts

• Annual summer herb up to 1 m high, usually erect though some varieties twine. The plant is entirely covered with fine brown or grey hair.
• Cultivated soybean, Glycine max (L.) Merr., is a diploidized tetraploid (2n=40).
• Soybean is grown primarily for the production of seed, has a multitude of uses in the food and industrial sectors, and represents one of the major sources of edible vegetable oil and of proteins for livestock feed use.
• Soybean is commonly considered one of the oldest cultivated crops, native to North and Central China. The oldest recording of soybeans made by emperor of China, Sheng Nung, is dated by the year 2838 B.C.
• Soybeans contain 37-40% proteins and 18-22% fat, most of which is represented by essential fatty acids. Rest of soybeans' content consists of carbohydrate - mostly oligosaccharides and fiber.
• Soybeans and a majority of soy-enriched foods are rich in isoflavones. Isoflavones (so-called phytoestrogens) are compounds that structurally similar to the human estrogen (estradiol) but much less potent due to weaker affinity with estrogen receptor (ER). Because of this similarity, isoflavones have been suggested to prevent many kinds of hormone-dependent diseases such as breast and prostate cancer, obesity, post-menopausal syndrom, and several others. Also concerns were raised that due to their estrogenic activity excess of isoflavones may lead to infertility in men, hypothyroidism, liver and other diseases. So far most of these claims were not robustly supported by in vitro as well as in vivo experiments.

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Developmental stages (life cycle)

Life Cycle Stages

• Seed A soybean plant can produce as many as 400 pods, with two to twenty pods at a single node. Each pod contains one to five seeds. MeSH
  • Dormant seed
  • Germinating seed MeSH
• Vegetative Also called V-stages. V stages after VC are defined and numbered by the upper, fully-developed leaf node on the main stem.
  • Seedling MeSH First 2 weeks after planting.
    • Emergence VE stage, 5-10 days after planting
    • Cotyledon stage VC stage, begins when cotyledons (embryonic leaves) are fully expanded, lasts for about 7-10 days during which cotyledons supply the nutrient needs of the young plant.
    • Trefoil V1, first trifoliolate stage, first trifoliolate is fully emerged and opened. V stages will now begin appearing around every three to five days through V5.
  • Second node Active nitrogen fixation from the bacteria is just beginning to occur; plant age is about 20-25 days.
  • Third node Plant is about 7-9 inches tall with four nodes (three unfolded leaflets).
  • Fourth node V4 stage
  • Fifth node V5; V5 is about 1 week from R1 or first flower. The total number of nodes that the plant can produce is established.
  • Sixth node V6 stage; plants are 12-14 inches tall with 7 nodes with unfolded leaflets. Unifoliolate and cotyledons may have senesced from the plant.
• Reproductive
  • Flowering
    • Early flowering R1 stage, first flower. Plant is 15-18 inches tall and structured as a V7-V10 palnt. Flowering always initiates on the third to sixth node and progresses up and down.
    • Full bloom stage R2 stage. An open flower is seen at one of the two top nodes of the main stem. The plant has accumulated about 25% of its total dry weight and has obtained about 50% of its mature height.
  • Pod development
    • Late flowering R3 stage, beginning pod stage. Plants can be up to 23-32 inches tall and can be at the V11-V17 stage. A pod on the upper four nodes is 3/16 inch long.
    • Full pod stage R4 stage; rapid pod growth; beginning of seed development.
  • Seed development
    • Beginning seed stage R5, the plant at this stage has seed at least 1/8 inch long in one of the pods on one of the four upper nodes of the main stem. About halfway through this stage, the plant attains its maximum height and node number.
    • Full seed stage R6 stage; green bean stage. Stage initiates with a pod containing a green seed that fills the pod cavity on at least one of the four top nodes of the main stem. After this stage rapid leaf senescing begins.
  • Ripening Plant maturation
    • Beginning maturity R7 stage; one mature pod (brown or tan in color).
    • Mature R8 stage; full maturity stage; 95% of pods on the plant are mature.

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References

• Barrett JR. The science of soy: what do we really know? Environ Health Perspect. 2006 Jun;114(6):A352-8.

  

  

  G-force. The dominant isoflavone in soy is genistein (above), which within soy is almost always bound to a sugar molecule, producing genistin (below). Once genistin enters the digestive tract, it releases its sugar. Most of the "free" genistein is subsequently reconjugated into glucuronides or sulfates.

  

  The culture question. Early research looked to the differences in soy consumption between Asian and Western diets to explain differences in disease rates, but results are far from conclusive.

• Brown VJ. Better bonding with beans. Environ Health Perspect. 2005 Aug;113(8):A538-41.

  

• Messina MJ, Wood CE. Soy isoflavones, estrogen therapy, and breast cancer risk: analysis and commentary. Nutr J. 2008 Jun 3;7:17.
• Free full text articles in PubMed: major topic "Soybeans"

Websites

• Soybean Growth and Management Quick Guide
• Reproductive Soybean Development and Soybean Aphid Thresholds (University of Wisconsin - Extension)

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