<p style="text-align: justify;"><big><b>General Description</b></big></p>

<p style="text-align: justify;">This description has been adapted from an OECD consensus document on the biology of <i>Glycine max</i> that is a available from http://www.oecd.org/ehs/ehsmono/Soybean.htm Cultivated soybean, <i>Glycine max</i> (L.) Merr., is a diploidized tetraploid (2n=40), in the family Leguminosae, the subfamily Papilionoideae, the tribe Phaseoleae, the genus Glycine Willd. and the subgenus Soja (Moench). It is an erect, bushy herbaceous annual that can reach a height of 1.5 metres. Three types of growth habit can be found amongst soybean cultivars: determinate, semi-determinate and indeterminate (Bernard and Weiss 1973). Determinate growth is characterised by the cessation of vegetative activity of the terminal bud when it becomes an inflorescence at both axillary and terminal racemes. Determinate genotypes are primarily grown in the southern USA (Maturity Groups V to X). Indeterminate genotypes continue vegetative activity throughout the flowering period and are grown primarily in central and northern regions of North America (Maturity Groups 000 to IV). Semi-determinate types have indeterminate stems that terminate vegetative growth abruptly after the flowering period. None of the soybean varieties are frost tolerant, and they do not survive freezing winter conditions. The primary leaves are unifoliate, opposite and ovate, the secondary leaves are trifoliolate and alternate, and compound leaves with four or more leaflets are occasionally present. The nodulated root system consists of a taproot from which emerges a lateral root system. The plants of most cultivars are covered with fine trichomes, but glabrous types also exist. The papilionaceous flower consists of a tubular calyx of five sepals, a corolla of five petals (one banner, two wings and two keels), one pistil and nine fused stamens with a single separate posterior stamen. The stamens form a ring at the base of the stigma and elongate one day before pollination, at which time the elevated anthers form a ring around the stigma. The pod is straight or slightly curved, varies in length from two to seven centimetres, and consists of two halves of a single carpel which are joined by a dorsal and ventral suture. The shape of the seed, usually oval, can vary amongst cultivars from almost spherical to elongate and flattened. The Soybean is grown as a commercial crop in over 35 countries. The major producers of soybeans are the USA, China, North and South Korea, Argentina and Brazil. 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. A major food use in North America and Europe is as purified oil, utilised in margarines, shortenings and cooking and salad oils. It is also used in various food products, including tofu, soya sauce, simulated milk and meat products. Soybean meal is used as a supplement in feed rations for livestock. Industrial use of soybeans ranges from the production of yeasts and antibodies to the manufacture of soaps and disinfectants. Soybean is commonly considered one of the oldest cultivated crops, native to North and Central China (Hymowitz 1970). The first recording of soybeans was in a series of books known as Pen Ts&#39;ao Kong Mu written by the emperor Sheng Nung in the year 2838 B.C., in which the various plants of China are described. Historical and geographical evidence suggests that soybeans were first domesticated in the eastern half of China between the 17th and 11th century B.C. (Hymowitz 1970). Soybeans were first introduced into the United States, now a major producer, in 1765 (Hymowitz and Harlan 1983).</p>

<p style="text-align: justify;"><big><b>Agronomic Practices</b></big></p>

<p style="text-align: justify;">Soybean is a quantitative short day plant and hence flowers more quickly under short days (Garner and Allard 1920). As a result, photoperiodism and temperature response is important in determining areas of cultivar adaptation. Soybean cultivars are identified based on bands of adaptation that run east-west, determined by latitude and day length. In North America, there are thirteen maturity groups (MG), from MG 000 in the north (45&deg; latitude) to MG X near the equator. Within each maturity group, cultivars are described as early, medium or late maturing. The seed will germinate when the soil temperature reaches 10&deg;C and will emerge in a 5-7 day period under favourable conditions. In new areas of soybean production an inoculation with Bradyrhizobium japonicum is necessary, for optimum efficiency of the nodulated root system. Soybeans do not yield well on acid soils and the addition of limestone may be required. Soybeans are often rotated with such crops as corn, winter wheat, spring cereals, and dry beans.</p>

<p style="text-align: justify;"><big><b>Centres of Origin</b></big></p>

<p style="text-align: justify;"><i>Glycine max</i> belongs to the subgenus Soja, which also contains <i>G. soja</i> and <i>G. gracilis</i>. <i>Glycine soja</i>, a wild species of soybean, grows in fields, hedgerows, roadsides and riverbanks in many Asian countries. Wild soybean species are endemic in China, Korea, Japan, Taiwan and the former USSR, but do not exist naturally in North America. Cytological, morphological and molecular evidence suggest that <i>G. soja</i> is the ancestor of <i>G. max</i>. <i>Glycine gracilis</i> is considered to be a weedy or semi-wild form of <i>G. max</i>, with some phenotypic characteristics intermediate to those of <i>G. max</i> and <i>G. soja</i>. <i>Glycine gracilis</i> may be an intermediate in the speciation of <i>G. max</i> from <i>G. soja</i> (Fekuda 1933) or a hybrid between <i>G. soja</i> and <i>G. max</i> (Hymowitz 1970).</p>

<p style="text-align: justify;"><big><b>Reproductive Biology</b></big></p>

<p style="text-align: justify;">The Soybean is considered a self-pollinated species, propogated commercially by seed. Artificial hybridisation is used for cultivar breeding. The soybean flower stigma is receptive to pollen approximately 24 hours before anthesis and remains receptive 48 hours after anthesis. The anthers mature in the bud and directly pollinate the stigma of the same flower. As a result, soybeans exhibit a high percentage of self-fertilisation and cross pollination is usually less than one percent (Caviness 1966). 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. Neither the seedpod, nor the seed, has morphological characteristic that would encourage animal transportation.</p>

<p style="text-align: justify;"><big><b>Tendancy to Weediness</b></big></p>

<p style="text-align: justify;">Cultivated soybean seed rarely displays any dormancy characteristics and only under certain environmental conditions grows as a volunteer in the year following cultivation. If this should occur, volunteers do not compete well with the succeeding crop, and can easily be controlled mechanically or chemically. The soybean plant is not weedy in character. In North America, <i>Glycine max</i> is not found outside of cultivation. In managed ecosystems, soybean does not effectively compete with other cultivated plants or primary colonisers.</p>

<p style="text-align: justify;"><big><b>Inter-Species/Genus</b></big></p>

<p style="text-align: justify;">In considering the potential environmental impact following the unconfined release of genetically modified <i>Glycine max</i>, it is important to have an understanding of the possible development of hybrids through interspecific and intergeneric crosses with related species. The development of hybrids could result in the introgression of the novel traits into these related species and result in:</p>

<ul>
	<li style="text-align: justify;">the related species becoming more weedy</li>
	<li style="text-align: justify;">the introduction of a novel trait, with potential for ecosystem disruption, into related species.</li>
</ul>

<p style="text-align: justify;">For a trait to become incorporated into a species genome, recurrent backcrossing of plants of that species by hybrid intermediaries, and survival and fertility of the resulting offspring, is necessary. The subgenus Soja, to which <i>G. max</i> belongs, also includes <i>G. soja</i> Sieb. and Zucc. (2n=40) and <i>G. gracilis</i> Skvortz. (2n=40), wild and semi-wild annual soybean relatives from Asia. <i>Glycine soja</i> (2n=40) is a wild viny annual with small and narrow trifoliate leaves, purple flowers and small round brown-black seeds. It grows wild in Korea, Taiwan, Japan, Yangtze Valley, N.E. China and areas around the border of the former USSR. <i>Glycine gracilis</i>, an intermediate in form between <i>G. soja</i> and <i>G. max</i>, has been observed in Northeast China (Skvortzow 1927). Interspecific, fertile hybrids between <i>G. max</i> and <i>G. soja</i> (Sieb and Zucc.) (Ahmad <i>et al</i>. 1977; Hadley and Hymowitz 1973; Broich 1978), and between <i>G. max</i> and <i>G. gracilis</i> (Karasawa 1952) have been easily obtained. In addition to the subgenus Soja, the genus Glycine contains the subgenus Glycine. The subgenus Glycine consists of twelve wild perennial species, including <i>G. clandestina</i> Wendl., <i>G. falcata</i> Benth, <i>G. latifolia</i> Benth., <i>G. latrobeana</i> Meissn. Benth., <i>G. canescens</i> F.J. Herm., <i>G. tabacina</i> Labill. Benth., and <i>G. tomentella</i> Hayata. These species are indigenous to Australia, South Pacific Islands, China, Papua New Guinea, Philippines, and Taiwan (Hymowitz and Newell 1981; Hermann 1962; Newell and Hymowitz 1978; Grant 1984; Tindale 1984,1986). Hybrids between diploid perennial Glycine species show normal meiosis and are fertile. Early attempts to hybridise annual (subgenus Soja) and perennial (subgenus Glycine) species were unsuccessful. Although pod development was initiated, these eventually aborted and abscised (Palmer 1965; Hood and Allen 1980; Ladizinsky <i>et al</i>. 1979). Intersubgeneric hybrids were later obtained <i>in vitro</i> through embryo rescue, between <i>G. max</i> and <i>G. clandestina</i> Wendl; <i>G. max</i> and <i>G. tomentella</i> Hayata (Singh and Hymowitz 1985; Singh <i>et al</i>. 1987); and <i>G. max</i> and <i>G. canescens</i>, using transplanted endosperm as a nurse layer (Brou&eacute; <i>et al</i>. 1982). In all cases, the progeny of such intersubgeneric hybrids was sterile and obtained with great difficulty.</p>

<p style="text-align: justify;"><big><b>Introgression into Relatives</b></big></p>

<p style="text-align: justify;">Soybean can only cross with other members of Glycine subgenus Soja. The potential for such gene flow is limited by geographic isolation. Wild soybean species are endemic in China, Korea, Japan, Taiwan and the former USSR. These species are not naturalised in North America, and although they could occasionally be grown in research plots, there are no reports of their escape from such plots to unmanaged habitats.</p>

<p style="text-align: justify;"><big><b>Summary of Ecology of glycine max</b></big></p>

<p style="text-align: justify;"><i>Glycine max</i> (L.) Merr., the cultivated soybean, is a summer annual herb that has never been found in the wild (Hymonitz 1970). This domesticate is in fact extremely variable, due primarily to the development of soybean &quot;land races&quot; in East Asia. The subgenus Soja contains, in addition to <i>G. max</i> and <i>G. soja</i>, the form known as <i>G. gracils</i>, a form morphologically intermediate between the two. This is a semi-cultivated or weedy form, and is known only from Northeast China. <i>Glycine soja</i>, considered the ancestor of cultivated soybean, is an annual procumbent or slender twiner that is distributed throughout China, the adjacent areas of the former USSR, Korea, Japan and Taiwan. It grows in fields and hedgerows, along roadsides and riverbanks.</p>

<p><b><b>References</b></b></p>

<ol>
	<li>Ahmad, Q.N., E.J. Britten and D.E. Byth 1977 Inversion bridges and meiotic behaviour in species hybrids of soybeans. J. Hered. 68: 360-364.</li>
	<li>Bernard, R.L. and M.G. Weiss 1973 Qualitative Genetics. Soybeans, Production and Uses. B.E. Caldwell (ed.). Agronomy Series, American Society of Agronomy, Madison, Wisconsin, USA. pp. 117-154.</li>
	<li>Broich, S.L. 1978 The systematic relationships within the genus Glycine Willd. subgenus Soja (Moench) F.J. Hermann. M.S. thesis. Iowa State University, Ames.</li>
	<li>Brou&eacute;, P., J. Douglass, J.P. Grace and D.R. Marshall 1982 Interspecific hybridisation of soybeans and perennial Glycine species indigenous to Australia via embryo culture. <i>Euphytica</i> <b>31</b>: 715-724.</li>
	<li>Caviness, C.E. 1966 Estimates of natural cross-pollination in Jackson soybeans in Arkansas. <i>Crop Sci</i>. <b>6</b>: 211.</li>
	<li>Fekuda, Y. 1933 Cytological studies on the wild and cultivated Manchurian soybeans (Glycine L.). <i>Jap. J. Bot.</i> <b>6</b>: 489-506.</li>
	<li>Garner, W. W. and H. A. Allard 1920 Effect of the relative length of day and night and other factors of the environment on growth and reproduction of plants. <i>J. Agric. Res.</i> <b>18</b>: 553-606.</li>
	<li>Grant, J.E. 1984 Interspecific hybridization in Glycine Willd. Subgenus Glycine (Leguminosae). <i>Aust. J. Bot</i>. <b>32</b>: 655-663.</li>
	<li>Hadley, H.H. and T. Hymowitz 1973 Speciation and cytogenetics. Soybeans, Production and Uses.</li>
	<li>B.E. Caldwell (ed.). Agronomy Series, American Society of Agronomy, Madison, Wisconsin, USA. pp. 97-116.</li>
	<li>Hermann, F. J. 1962 A revision of the genus Glycine and its immediate allies, USDA Tech. Bull. 1268: 1-79.</li>
	<li>Hood, M.J. and F.L. Allen. 1980 Interspecific hybridization studies between cultivated soybean, Glycine max and a perennial wild relative, G. falcata. Agron. Abst. American Society of Agronomy, Madison, WI. pp.58.</li>
	<li>Hymowitz, T. 1970 On the domestication of the soybean. <i>Econ. Bot</i>. <b>24</b>: 408-421.</li>
	<li>Hymowitz, T. and C.A. Newell 1981 Taxonomy of the genus Glycine, domestication and uses of soybeans. <i>Econ. Bot.</i> <b>37</b>: 371-379.</li>
	<li>Hymowitz, T. and J.R. Harlan 1983 Introduction of soybeans to North America by Samuel Bowen in 1765. <i>Econ. Bot.</i> <b>37</b>: 371-379.</li>
	<li>Karasawa, K. 1952 Crossing Experiments with <i>Glycine soja</i> and <i>G. gracilis</i>. <i>Genetica</i> <b>26</b>:357-358.</li>
	<li>Ladizinsky G., Newell C.A. and T. Hymowitz 1979 Wild Crosses in soybeans: prospects and limitations. <i>Euphytica</i> <b>28</b>:421-423.</li>
	<li>Newell, C. A. and T. Hymowitz 1978 A reappraisal of the subgenus Glycine. <i>Am. J. Bot</i>. <b>65</b>: 168-179.</li>
	<li>Palmer, R.G. 1965 Interspecific hybridization in the genus Glycine. M.S. thesis. Universiy of Illinois, Urbana, IL.</li>
	<li>Singh, R. J. and T. Hymowitz 1985 An intersubgeneric hybrid between <i>Glycine tomentella</i> Hayata and the soybean, <i>G. max</i>. (L.) Merr. <i>Euphytica</i> <b>34</b>: 187- 192.</li>
	<li>Singh, R. J., K.P. Kollipara and T. Hymowitz 1987 Intersubgeneric hybridization of soybeans with a wild perennial species, Glycine clandestina Wendl. <i>Theor. Appl. Genet</i>. <b>74</b>: 391-396.</li>
	<li>Skvortzow, B.V. 1927 The soybean - wild and cultivated in Eastern Asia. Proc. Manchurian Res. Soc. Publ. Ser. A. Natural History. History Sect. No. 22:1-8.</li>
	<li>Tindale, M.D. 1984 Two eastern Australian species of Glycine Willd. (Fabaceae). <i>Brunonia</i> <b>7</b>: 207-213.</li>
	<li>Tindale, M.D. 1986 Taxonomic notes in three Australian and Norfolk island species of Glycine Willd. (Fabacea: Phaseolae) including the choice of a neotype of G. clandestine Wendl. <i>Brunonia</i> <b>9</b>: 179-191.</li>
</ol>
