Glycine max (PROSEA)
Glycine max (L.) Merr.
- Protologue: Interpret. Rumph. Herb. Amboin. 274 (1917).
- Family: Leguminosae
- Chromosome number: 2n= 40
- Phaseolus max L. (1753),
- Glycine hispida (Moench) Maxim. (1873),
- Soja max (L.) Piper (1914).
- Soyabean, soybean (En)
- soia, soja, pois oléagineux de Chine (Fr)
- Indonesia: kedelai, kacang jepun, kacang bulu
- Malaysia: kacang soya, kacang bulu rimau, kacang jepun
- Philippines: utau, soybean, balatong
- Burma: lasi, pengapi, peryatpym
- Cambodia: sândaèk sieng, sândaèk an gen sar
- Vietnam: dâu tuong, dâu nành, quantan
- Thailand: thua lueang, thua phra lueang, thua rae
- Laos: thwàx khôn, thwàx tê.
Origin and geographic distribution
Soyabean originated as a domesticate in the eastern half of north China around the 11th century BC. From there it spread to Manchuria, Korea, Japan and the USSR where the centuries-long process of domestication took place. Soyabeans were mentioned in Japanese literature around 712 AD. Soyabean was introduced to Korea between 30 BC and 70 AD. In 1765 Samuel Bowen introduced soyabean to the USA from China. Soyabeans were introduced from China, Japan and Korea to most of the South and South-East Asian countries through the 'silk route'.
Soyabeans are used in the preparation of a variety of fresh, fermented and dried food products like milk, tofu, tempeh, miso, yuba, soya sauce and bean sprouts. Soyabeans are used not only for food but they also serve as a cure for various diseases and as body ailments. Soyabeans (preferably black ones) are included in medicinal prescriptions to improve the function of the heart, liver, kidneys, stomach and bowels.
Soyabeans are used to extract oil for food and for numerous industrial purposes. As an edible oil it enters the market as salad oil, cooking oil, margarine and shortening. The cake remaining after oil extraction is rich in protein and predominantly used as animal feed. Modern food uses of soyabean proteins include defatted flours and grits, concentrates, isolates, textured flours and textured concentrates.
Production and international trade
Total world soyabean area is around 52.6 million ha and production of soyabeans is around 96 million t. The USA has 48% of the total area with 56% of total world production. Brazil ranks second with 10 million ha and a production of about 16 million t. China is the leading producer in Asia with 10 million t from about 7.5 million ha. Among the South and South-East Asian countries, India and Indonesia were the major producers in 1986 with 1.0 and 1.2 million t from 1.35 and 1.2 million ha respectively. Thailand produced 334 000 t from 244 000 ha in the same year. The Philippines produced 8 000 t from 8 000 ha, Vietnam 120 000 t from 14 900 ha. The Asian countries as a whole import around 8.0 million t of beans, 1.5 million t of oil, and 1.8 million t of soyabean meal annually. Indonesia and Malaysia import about 3 000 t and 2 000 t beans/year respectively. From the region, only Thailand exports around 1000 t soyabeans annually. Asia produces only half of its domestic demand, the rest is imported. Even though the area is small and the production is low in Asia if compared with the leading producers like the USA and Brazil, almost all Asian countries produce and consume soyabeans. In 1986 the USA exported 21.6 million t of soyabeans. Brazil and Argentina are the next major soyabean exporters. Among the importers of soyabean in Asia, the scene is dominated by China, Japan, Taiwan and Korea. Indonesia, Malaysia and the Philippines also import soyabean. The world price of soyabean is around US$ 220/t.
Soyabean growers in India, Indonesia, Thailand and other Asian countries are predominantly smallholders; estates are rather rare.
Per 100 g edible portion dry soyabeans contain: water 10 g, protein 35 g, fat 18 g, carbohydrates 32 g, fibre 4 g, ash 5 g. The energetic value averages 1680 kJ/100 g. The protein and oil content varies from 35-54% and 13.3-26.7% respectively. Soyabeans contain 80% meal and 18% oil, the meal/oil ratio is 4.4:1. Soyabean oil is high in polyunsaturated fatty acids, and it is expecially rich in linoleic acid. It contains no cholesterol, it is high in vitamin E and an important by- product of the oil is lecithin. Methionine supplementation to the diet is not required when daily intake of soyabean protein is 6 g or more. Heat labile antinutritional factors of soyabean are trypsin inhibitors, hemagglutinins, goitrogen, antivitamins and phytates, while heat stable ones are saponins, estrogens, flatulence factors, and lysinoalanine. The weight of 100 soyabean seeds varies from 5-70 g. Small beans (less that 10 g/100) are used for making beansprouts while larger beans (> 30 g/100) are directly used as vegetable. Soyabeans serve as a major source of Ca and vitamins B-1 and C in the oriental diet. Soyabean protein concentrates and isolates contain 67% and 93% protein respectively.
- Usually an erect bushy annual herb, 0.2-1.5 m tall, sometimes viny, brownish or greyish pubescent. Taproot branched, up to 2 m long, side roots spreading up to 2.5 m distance in upper 10-15 cm; in the presence of Rhizobium japonicum bacteria, root nodules are formed. Stem branched or unbranched, becoming woody.
- Leaves alternate, trifoliolate, glabrous to pubescent; petiole long, especially in lower leaves; leaflets ovate to lanceolate, 3-10 cm × 2-6 cm, entire, base rounded, apex acute to obtuse.
- Inflorescences axillary and/or terminal racemes with 3-30 flowers; flowers small, papilionaceous, purple or white; calyx tubular, with 2 upper and 3 lower unequal lobes, persistent; keel shorter than the wings, not fused along the sutures; stamens 10, diadelphous; style curved with capitate stigma.
- Pods slightly curved and usually somewhat compressed, 3-15 cm × 1 cm, dehiscent, containing (1-) 2-3 (-5) seeds.
- Seeds usually globose, yellow, green, brown or black or blotched and mottled in combinations of these colours; hilum small.
- Seedlings with epigeal germination; primary leaves simple and opposite.
Growth and development
In 5-15 days after sowing the seedlings emerge. Subsequently in 3-10 days the cotyledons unfold and in the next 3-10 days the first trifoliolate leaf unfolds. Above the primary leaf, 8-24 nodes may develop. Flowering starts from 25 to more than 150 days after sowing, depending on daylength, temperature and cultivar; flowering can take 1-15 days. Pod formation takes about 7-15 days, seed filling 11-20 days, ripening to harvest 7-15 days.
The entire cycle from sowing to maturity varies from 65 to more than 150 days. Soyabean is a quantitative short-day plant, hence development to maturity is usually shorter under short-day than under long-day conditions. At higher elevations with lower temperatures flowers are usually cleistogamous. Soyabean is normally self-pollinated and completely self- fertile with less than 1% cross-pollination. The number of pods per plant varies from a few to more than 1 000.
Other botanical information
A great number of cultivars is recognized in the Far East which vary in time to maturity, height and plant type, size, colour, oil and protein content of the seed, the uses to which they are put. For oil production yellow seeds are preferred. For immature seeds to be used as vegetable large yellow- or green-seeded forms are preferred. Hay and fodder cultivars are usually brown- or black-seeded and the plants are often twining. Early maturing Indonesian cultivars include: 'Lokon', 'Guntur' and 'Tidar'; other widely used Indonesian cultivars are: 'Orba', 'Wilis', 'Kerinci', 'Dempo' and 'Galunggung'. 'SJ4' and 'SJ5' are popular cultivars in Thailand. A narrow-leaflet cultivar, 'Sukothai 1', is high yielding, resistant to bacterial pustule, and widely grown during the rainy season in Thailand. Another early-maturing, high-yielding cultivar, 'Nakhonsawan 1', is also popular in Thailand. The following cultivars are widely grown in India: 'Ankur', 'Alankar', 'Shilajeet', 'Gaurav', 'Durga', 'KHSb-2' and 'PB-1'. In Taiwan 'KS No. 10' is a cultivar with narrow leaflets, which is resistant to bacterial pustule. 'KS No. 1' is a newly released vegetable soyabean cultivar.
Thirteen maturity groups (MG) are recognized in the USA and Canada. The 000, 00 and 0 MG are early and adapted to the extreme northernmost latitudes; MG IX and X are adapted to the equatorial latitudes. Although there are wet season and dry season soyabeans, no definite classification has been made based on wet and dry seasons. Considerable genetic diversity exists for the number of days needed to reach maturity under short-day conditions in the world soyabean germplasm collection.
Soyabean is grown from the equator to latitude 55°N or 55°S, and from below sealevel to altitudes close to 2000 m. Soyabean is a short- day plant. Some cultivars respond as quantitative short-day plants and some are almost completely insensitive to photoperiod. The response to photoperiod is readily modified by temperature. Differences in photoperiod, temperature and the relative sensitivity of different genotypes to these factors dictate the rates and durations of phenological development of soyabean, whether they are grown in temperate areas or in the tropics. Temperatures below 21°C and above 32°C can reduce floral initiation and pod set, extreme temperatures above 40°C are detrimental for seed production. If water is available soyabeans can be grown year-round in the tropics and subtropics.
The daily water use of soyabean is as much as 7.6 mm, requiring 500 mm in total for a good crop. Drought stress during flowering reduces pod set, but it reduces yield more at pod-filling stage than at flowering stage. Soyabeans can tolerate short periods of waterlogging, however, seed weathering is a serious problem in the rainy season.
Soyabeans are sensitive to low pH, in acid soils liming is essential to bring the pH to 6.0 or 6.5 to obtain optimum soyabean production. Mn, Fe and Al toxicities in low-pH soils, and Mn and Fe deficiencies in high-pH soils are common. Cultivars with tolerance to Fe deficiency are available.
Soyabeans are propagated by seed. They are cultivated both as a sole crop and in various intercropping systems with maize, cassava, sorghum, banana, sugarcane, rubber, oil palm, coconut and fruit trees. In maize and sorghum, soyabeans can be intercropped with two rows. Soyabeans are also grown on paddy-rice bunds. Without tillage, soyabeans are sown at each rice stubble in rows with a spacing of 25 × 25 cm or 20 × 20 cm. In tilled fields, soyabeans are sown in rows 40-50 cm apart and within rows the seeds are either drilled or planted at 10 cm spacing. Within each hill two to three seeds are planted. Sowing by broadcasting the seeds after rice harvest is also practiced. In Indonesia some farmers presoak the seed overnight and sow the following day by broadcasting. Most of the soyabean farmers in South and South-East Asia are smallholders.
Weed control is essential and the timing and frequency varies with season, cultivar and location. Irrigations at flowering and at seed filling stages are essential to have optimum yield. More frequent irrigations are needed in sandy well-drained soils compared to heavy clay soils.
To obtain 1 t of seeds, soyabean plants must absorb 80 kg N/ha. About half of this N is provided by symbiotic N-fixation byRhizobium. The remainder should come from the soil or from applied N. The P and K uptake of soyabean is around 90 and 85 kg/ha respectively.
Diseases and pests
Among the diseases, soyabean rust caused by Phakopsora pachyrhizi can reduce yields by as much as 90%. Other important diseases in the region are: bacterial pustule (Xanthomonas campestris pv. phaseoli), downy mildew (Peronospora manshurica), anthracnose (Colletotrichum truncatum and Glomerella glycines), purple seed stain (Cercospora kikuchii), pod and stem blight (Phomopsis sojae (teliomorph) Diaporthe phaseolorum var.sojae), soyabean mosaic virus, yellow mosaic virus and various seedling diseases. Among the insect pests, the beanflies (also called stem miners) Melanagromyza sojae, M. dolichostigma, Ophiomyia centrosematis and O. phaseoli can cause 100% yield loss. Pod feeders such as stink bugs (e.g. Nezara viridula, Riptortus clavatus, R. linearis and Piezodorus hybneri), pod borers (e.g. Leguminivora glycinivorella, Etiella zinckenella, E. hobsoni, Heliothis armigera and Maruca testulalis), and a number of defoliators (e.g. Heliothis armigera, Spodoptera litura, S. exigua, Plusia chalcites, Heydelepta indicata, Lamprosema indicata, Phaedonia inclusa and Diacrisia obliqua), are important risk factors in soyabean production. Nematodes can also reduce yields. At present, chemical control is the only means of controlling the mentioned pests. Socio-economics and availability of resources are major considerations in the application of chemical control methods.
Early maturing cultivars can be harvested for grain as early as 70 days after planting, while late maturing cultivars need up to 160 days. The plants are cut near the ground or pulled with their roots when most leaves senesced and have turned yellow, and when the pods have turned brown or black. Harvesting by combine is common in developed countries but has yet to be widely adopted in developing countries. Vegetable soyabeans are harvested when the pods are still green but the seeds fill the pod cavity.
The average yield of grain soyabean in South-East Asia in 1986 was 1073 kg/ha against 1841 kg/ha for the world. The average yield in Indonesia was 999 kg/ha, whereas in India it was only 741 kg/ha. Thailand had an average yield of 1369 kg/ha and the USA produced 2271 kg/ha. The maximum yield obtained in South-East Asia was more than 5000 kg/ha. The yield of intercropped soyabean ranged from 0.6-2.0 t/ha in experiments. The marketable pod yield of vegetable soyabean in Taiwan was about 6-8 t/ha.
Handling after harvest
After harvest the plants with the pods are dried in the sun. The dried plants are trampled by cattle or tractor which facilitates threshing. Threshing is also done by beating with sticks. After threshing the seeds are winnowed, cleaned and prepared either for storage or for market. Deterioration of the seed quality in storage is a problem in the tropics and is attributable to inappropriate storage conditions. In vegetable soyabeans the whole pods are marketed either fresh or frozen. In some cases the seeds are shelled from the pods like green peas and marketed. Frozen vegetable soyabean export is a multimillion dollar industry in Taiwan.
Five provinces in China maintain collections with a total of 12 390 accessions. At AVRDC the soyabean germplasm collection by the end of 1987 totalled around 12 505, among which several are duplicates. The AVRDC collection includes most of the USDA collection and germplasm from various Asian countries. The USDA holds more than 10 000 accessions in their collections in Illinois and Mississippi. India has 5 800 accessions. The indigenous soyabeans in Indonesia have been collected and maintained at the Malang Research Institute for Food Crops. Japan has an excellent germplasm facility storing 3 541 accessions. The Republic of South Korea has collected and evaluated 3 130 locally cultivated and wild soyabeans. Thailand has a duplicate collection from Japan and the AVRDC.
The major breeding objectives are: improvement in yield potential, improved disease and pest tolerance, early maturity, good seed quality, improved adaptation to specific environments, weathering resistance, promiscuous nodulation in specific instances, development of tropically-adapted cultivars and developing cultivars for specific purposes such as vegetable soyabeans and bean sprouts. Improvement of soya oil quality and elimination of beany flavour are additional objectives. Selection for less sensitivity to photoperiod and temperature and tolerance to major diseases such as soyabean rust, bacterial pustule, downy mildew and virus diseases would enhance yield stability across environments and locations.
Glycine soja (L.) Sieb. & Zucc. is the wild annual relative of G. max. It is sometimes considered as a subspecies of soyabean: G. max subsp. soja (Sieb.& Zucc.) Ohashi. G. tomentella Hayata has aneuploids and polyploids and is found in Australia, south China, Taiwan, the Philippines and Papua New Guinea. G. tabacina (Labill.) Benth. with diploid and polyploid types is found in the above-mentioned countries, as well as on the Ryukyu Islands, Mariana, and other South Pacific Islands. All the wild relatives have slender viny stems and small dark-coloured seeds with hard seed coat which require scarification for germination. The following perennial Glycine species are diploid and are found in Australia: G. clandestina Wendl; G. clandestina var. sericea Benth.; G. falcata Benth.; G. latifolia (Benth.) Newell & Hymowitz; G. latrobeana (Meissn.) Benth. and G. canescens F.J. Herm. The newly described G. argyrea Tindale and G. cyrtoloba Tindale might not be the last relatives to be detected in the Australian region. G. javanica, once considered as a relative of G. max, has been removed from the genus and placed in the genus Neonotonia.
Although G. soja, G. tabacina and G. tomentella are readily available, only G. soja is readily crossable. G. canescens appears to have single gene resistance to several races of the Phakopsora pachyrhizi in Australia. Some of the annual wild species like G. tomentosa and some perennial species appear to have adaptation to drought, high soil pH and disease stress.
The world soyabean production is expected to double in the next two decades. Many farmers in both developed and developing countries are harvesting considerably higher yields than the average yields for their countries. Better adapted and improved cultivars are expected to increase and stabilize the yield. Increase in the number of scientists and emphasis by national policy to increase soyabean production will lead to higher yields. Collection and exploitation of indigenous germplasm, enhanced disease and pest resistance, improvement in nutritional quality and identifying appropriate management practices to exploit the maximum economic yield potential of cultivars should be given priority.
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