Soybean

Glycine max (L.) Merr.

Synonyms - Phaseolus max

Order: Fabales

Family: Fabaceae

Names:

Glycine
Max
Soybean

Other Names:

Summary:

An erect, brown-hairy, annual, summer growing leguminous crop that is grown for the protein and oil rich grain. It may grow to 2 m tall but is usually less than 1 m tall.

Description:

Cotyledons:

Two.

Leaves:

Alternate. 3 leaflets (trifoliate).
Stipules - Parallel sided.
Petiole - Long
Blade (of leaflets) - Egg shaped to elliptical, 30-150 mm long. Red brown hairs. Tip pointed to rounded. Sides curved. Base tapered.

Stems:

Erect, 300-2000 mm tall with reddish brown hairs.

Flower head:

Axillary spray (raceme) of 5-8 flowers.

Flowers:

Small pink to white pea type flowers.
Ovary - many ovules. Style glabrous. Stigma terminal.
Calyx - 5-7 mm long, bell shaped, 2-lipped, the upper lip composed of 2 almost united sepals, the lower lip of 3 sepals.
Petals (corolla) - purple, pink or white, 5.5-7 mm long. Standard petal slightly ear like (auriculate) at the base, smooth and hairless (glabrous).
Stamens - Filaments united into a tube (monadelphous).
Anthers - All are similar (uniform).

Fruit:

2.5-8.5 cm long, 8-15 mm broad, 2-4-seeded, parallel sided (linear), brown and hairy, drooping (pendant) pod.
It is constricted between seeds and the valves spiral after seed is shed (dehiscence).

Seeds:

6-11 mm diameter. Short lateral hilum. Small scale-like aril.

Roots:

Have nitrogen fixing nodules.

Key Characters:

Trifoliate leaves.
Parallel sided stipules.
Purple, pink or white pea type flowers.
Brown hairy pods with 2-4 round seeds

Biology:

Life cycle:

Annual herb. Seed is sown in November to January and the crop harvested in April to May.

Physiology:

Fixes nitrogen but usually requires inoculation before sowing as the Soybean Rhizobium is not a natural inhabitant of Australian soils and is from a different group to other legumes.
Sensitive to moisture stress especially during flowering and pod development.
Seed contains 19-23% oil and 40-45% protein.
Australian cultivars flower more rapidly in short day conditions

Reproduction:

By seed.

Flowering times:

Summer.

Seed Biology and Germination:

Will germinate from up to 80 mm deep but grows more strongly when planted shallower.

Vegetative Propagules:

Hybrids:

Many commercial cultivars exist.

Allelopathy:

Population Dynamics and Dispersal:

Spread mainly by intentional planting.

Origin and History:

Derived from Asian species.
Domesticated in China around the 11th century BC (Hymowitz, 1970).

Distribution:

NSW, NT, QLD, SA, VIC, WA.
Not naturalised.

Habitats:

Climate:

Sub tropical.
In Australia it is mainly grown in the subtropics between 26-330S as an irrigated and dry land crop.

Soil:

Grows in most soil types. Prefers pH of 6-6.5 and soils with good moisture storage characters.

Plant Associations:

Significance:

Beneficial:

High protein grain.
Food. Fodder. Oils used for margarine and edible, salad and cooking oils.
Meal of seed after oil extraction has 50% protein and used for pig and poultry feed.
Honey plant.
Fruit used in herbal medicine. Associated with reduced ovulation rate (coumestrol), wound healing (allantoin) and haemolytic, insecticidal (soyasaponins). Soybean sprouts show oestrogen-like activity and antispasmodic activity.

Detrimental:

Toxicity:

Not recorded as toxic.

Symptoms:

Treatment:

Legislation:

None.

Management and Control:

Initial growth is slow and it is a weak competitor with weeds.

Thresholds:

Eradication strategies:

Herbicide resistance:

Biological Control:

Susceptible to Phytophthora stem rot.
Insect pests include sucking bugs, caterpillars and stem borers.

Related plants:

Silky Glycine (Glycine canescens)
Twining Glycine (Glycine clandestina)
Clover Glycine (Glycine latrobeana)
Wild Soybean (Glycine soja)
Glycine Pea (Glycine tabacina)
Woolly Glycine (Glycine tomentella)
Glycine falcata

Plants of similar appearance:

References:

Flora of Pakistan.

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #591.1.

Reid, R.L. (1990) The Manual of Australian Agriculture. (Butterworths, Sydney). P106-108.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.