- Protologue: Sp. pl.: 721 (1753); Gen. pl. ed. 5: 322 (1754).
- Family: Leguminosae - Papilionoideae
- Chromosome number: x= 5 or 6; L. albus: 2n= 30, 40, 48, 50; L. angustifolius: 2n= 40, 48; L. luteus: 2n= 46, 48, 50, 52, 104; L. mutabilis: 2n= 42, 48
Major species and synonyms
- Lupinus albus L., Sp. pl.: 721 (1753), synonyms: L. termis Forssk. (1775), L. graecus Boissier & Spruner (1843).
- Lupinus angustifolius L., Sp. pl.: 721 (1753), synonyms: L. linifolius Roth (1787), L. reticulatus Desv. (1835), L. opsianthus Atabekova & Maissurjan (1969).
- Lupinus luteus L., Sp. pl.: 721 (1753), synonym: L. odoratus DC. (1825).
- Lupinus mutabilis Sweet, Brit. flow. gard., Ser. 1, 2. t. 130 (1825), synonym: L. cruckshanksii Hooker (1831).
- Lupin (En, Fr)
- Lupine (Am).
- L. albus : White lupin, Egyptian lupin (En). Lupin blanc (Fr).
- L. angustifolius : Blue lupin, narrow leaved lupin (En). Lupin petit bleu, lupin à feuilles étroites (Fr).
- L. luteus : European yellow lupin, yellow lupin (En). Lupin jaune (Fr).
- L. mutabilis : Andean lupin, South American lupin, pearl lupin (En). Tarwi, chocho (Sp).
Origin and geographic distribution
The origin of Lupinus is unknown; it is distributed over the Mediterranean region, where it occurs from southern Europe to the highlands of North and East Africa, and the American continent, where it is found in the western parts of North and South America, but not in the Amazon basin. Only 12 species are native to the Old World, including the cultivated species L. albus , L. angustifolius and L. luteus . L. albus originates from the Balkan and the Aegean region, L. angustifolius from southern Europe and L. luteus from the western Mediterranean. L. mutabilis is the main cultivated American species, originating from the Andean mountains.
Lupin domestication commenced relatively late: 4000-3000 BC. The cultivated species are grown worldwide, from cool temperate to subtropical and tropical areas.
Lupins are cultivated as green manure, for soil improvement and in pastures. Lupin has been used as green manure since ancient times. Ploughing in lupin at the flowering or early fruiting stage improves soil fertility. Intensive farming and its associated massive use of mineral fertilizers has largely displaced this practice, however. Lupins, especially L. albus , L. mutabilis , L. arboreus Sims and L. polyphyllus Lindley play a prominent role in erosion control, e.g. in Brazil, Peru, New Zealand and Germany. L. arboreus , the tree lupin, a native of California, is also used to consolidate coastal land and in reclamation of kaolin mine spoils.
The dry seed of sweet, alkaloid-free cultivars and de-bittered seed is used as fodder in concentrates, as fish feed and, to a lesser extent, for human nutrition. The alkaloid extracts obtained in industrial de-bittering of lupin seed are used as biostimulants and biological insecticides. The fat content of L. mutabilis is sufficiently high to justify the extraction of edible oil. L. luteus is of greatest interest as a protein-rich forage as it resprouts well from axillary buds and becomes woody later than other species. Flowering lupin makes good hay. Dry plants of bitter lupin, mainly cultivars of L. luteus with shattering pods, are eaten by sheep in arid zones during dry summers.
Several lupins are used medicinally. A decoction of the seed of L. albus is reported to increase the sugar tolerance in diabetic patients. Traditionally, seed of L. albus is used for a variety of ailments, e.g. as anthelmintic, carminative, deobstruent, diuretic and pectoral. Burning the seeds is said to drive away gnats. The asparagin-rich seed of L. angustifolius has been used in culture media for the production of tuberculin.
Production and international trade
About 2 million ha are cultivated with lupins world-wide, of which 60% is mainly for grain production and 40% for forage and green manure. The former Soviet Union (1 million ha) and Poland (285 000 ha), where L. luteus is the main species, account for over 90% of the area cultivated for fodder, while Australia is the leading grain producer with 700 000 ha of L. angustifolius . Australia and Chile are the main exporting countries of lupin grain, while the Korean Republic, the European Union and Japan are the leading importers. In Korea, lupin seed is mainly used in fish feed, in Japan and Indonesia for human consumption.
Hay from an immature lupin crop contains per 100 g dry matter: crude protein 32 g, fat 5 g, N-free extract 38 g, crude fibre 20 g, ash 4 g, P 0.45-0.5 g, Ca 0.55-0.6 g, Mg 0.35 g.
The most salient feature of lupin grain is its high protein content, ranking among the highest for legumes and ranging from 30-50% (28-38% for L. angustifolius) . The proteins contain only small amounts of sulphur-containing amino acids. L. mutabilis contains 13-23% fat, L. albus 10-14%, whereas all other cultivated species contain less than 7%. The carbohydrate content is 20-30%. The fibre content is inversely related to the size of the grain: 15-18% for L. luteus , 7-11% for L. mutabilis and only 3-10% for L. albus . The ash content varies from 2.5-5%, with little difference between species. The content of the major elements per 100 g dry matter is: P 0.6 g, K 1.1 g, Ca 0.3 g, Mg 0.2 g, Na 1 g. Lupin seed also contains appreciable amounts of ß-carotene, niacin, thiamine and, especially, choline.
Toxins reduce the nutritional value of lupin plants considerably. Toxic and bitter quinolizidine alkaloids are the main obstacle in using the seed and the rest of the lupin plant. Lupinine and sparteine are the most toxic components. Hydroxyluparine is another lupin alkaloid. The overall alkaloid content of bitter lupin seed per 100 g dry matter ranges from 0.3 g to over 3 g, while selected sweet cultivars contain 0.05-0.2 g. The alkaloids can be removed by boiling or steeping in water. Industrially, they are separated from lupin flour by solvent extraction.
The weight of 1000 seeds is 150-500 g for L. albus , 130-200 g for L. angustifolius , 110-180 g for L. luteus and 120-340 g for L. mutabilis .
Annual or perennial herbs or shrubs, erect to creeping; habit indefinite; taproot strong, deep. Stem branching to 5th-order laterals, glabrous or pubescent, up to 2 m long. Leaves digitately compound, long-petioled, 5-12 foliolate, heliotrope; stipules adnate to the base of the petiole. Inflorescence a terminal raceme, increasing in size with increasing branching order, 20-30-flowered; calyx bilabiate, divided almost to the base; corolla variously coloured, wings connate at the apex, keel beaked; stamens 10, monadelphous. Fruit a straight, compressed pod, usually constricted between the seeds, dehiscent, 3-12-seeded. Seed variable in shape, size and colour, with sunken hilum. Seedling with epigeal germination.
- L. albus . Short-hairy annual, up to 120 cm tall. Leaflets of lower leaves obovate, 25-35 mm × 14-18 mm, those of upper leaves obovate-cuneate, 40-50 mm × 10-15 mm, all mucronulate, nearly glabrous above, sparsely villous beneath, dark green; stipules setaceous. Inflorescence 5-10 cm long, sessile; flowers alternate; calyx 8-9 mm long, both lips shallowly dentate; corolla 15-16 mm long, white or blue. Pod 6-10 cm × 11-20 mm, shortly villous, glabrescent, yellow, 4-6-seeded. Seed orbicular-quadrangular, 8-14 mm in diameter, compressed or depressed, smooth, dull, light yellow, sometimes with dark variegation.
- L. angustifolius . Short-hairy annual, 20-80(-150) cm tall. Leaflets linear to linear-spatulate, 10-50 mm × 2-5 mm, glabrous above, sparsely villous beneath; stipules linear-subulate. Inflorescence 10-20 cm long; peduncle 1-3 cm long; flowers alternate; lower calyx lip 6-7 mm long, irregularly 3-dentate to subentire, upper lip about 4 mm long, 2-partite; corolla 11-13 mm long, blue. Pod 5-7 cm × 1-1.3 cm, shortly hirsute, yellow to black, 4-6-seeded. Seed ellipsoid, 7-8 mm long, smooth, dull, yellow-brown, dark brown or grey with yellow spots.
- L. luteus . Hairy annual, 25-80 cm tall. Leaflets obovate-oblong, 40-60 mm × 8-12 mm, mucronate, sparsely villous; stipules dimorphic, those of lower leaves subulate, 8 mm long, those of upper leaves linear-obovate, 22-30 mm × 2-4 mm. Inflorescence 5-16 cm long; peduncle 4-12 cm long; flowers verticillate, scented; lower calyx lip 10 mm long, shallowly 3-dentate, upper lip 6-7 mm long, 2-partite; corolla 13-16 mm long, bright yellow. Pod 4-5 cm × 1 cm, densely villous, black, 4-6-seeded. Seed orbicular-quadrangular, 6-8 mm × 4.5-6.5 mm, compressed, smooth, dull, black marbled with white, with a white curved line on each side.
- L. mutabilis . Erect, glabrous annual, 0.5-2.5 m tall. Stem generally slightly woody, more or less glabrous. Leaf (5-)7-9(-12)-foliolate; leaflets ovate to lanceolate or oblanceolate, about 6 cm long, glabrous, yellowish-green; petiole reddish-green to dark green. Inflorescence up to 60-flowered; flowers verticillate, fragrant; corolla 1-2 cm long, blue and/or pink and white, with yellowish eye. Pod up to 12 cm long, densely hairy when young, up to 9-seeded, almost indehiscent. Seed 0.5-1.5 cm in diameter, black, brownish black, white or white with a black or grey halo around the hilum.
Growth and development
During the vegetative phase, leaf rosettes are formed, their longevity depending on species, cultivar and environmental conditions. Flowering is initiated by the influence of vernalization and photoperiod, with major inter- and intraspecific differences. Lupins from the Old World are quantitative long-day plants, L. luteus being the most daylength-sensitive. L. mutabilis is either a scarcely daylength-sensitive short-day species or a day-neutral species. Flowering is stepwise: inflorescences appear on branches of a given order concomitantly with the flowering of inflorescences on the branches of the immediately preceding order. The length of the flowering period of an inflorescence decreases with increasing branching order. Fertilization is essentially autogamous, but is occasionally allogamous as well in some species and under certain environmental conditions. High temperatures and water stress are decisive in determining the end of flowering. The rate of fruit setting varies with the inflorescence order and usually averages 10-30%. When flowering has ceased, seeds grow rapidly and ripen virtually simultaneously on all branches.
Lupins nodulate with Rhizobium lupini and a crop can accumulate 130-240 kg N/ha. In tests in Australia with L. angustifolius , nodules appeared 4-6 weeks after sowing, while nitrogen-fixation started 2 weeks later. Nitrogen-fixation peaked at the beginning of flowering and remained constant until the beginning of seed filling and the onset of water stress; under optimal conditions it may continue until seed maturity and even leaf drop.
Other botanical information
Three centres of speciation or origin are distinguished: North and Central America, South America, and the Mediterranean-African region. The number of species in Lupinus is disputed. It was long estimated to be about 200, but recent opinion puts it at about 600 or even higher. The majority of the species occur in the Americas and also the new species are described from there. The 4 major cultivated species are quite variable and many cultivars and cv. groups are distinguished. Well-known cultivars of L. alba are: "Kiev", "Multolupa" and "Ultra"; of L. angustifolius : "Uniharvest", "Unicrop" and "Illyarrie".
The mean maximum temperature during the growing season is 15-25 °C. Higher temperatures and moisture stress hinder flowering and pod setting. Mediterranean species are cold-tolerant (-6 to -9 °C) during the vegetative period. On the other hand, L. mutabilis seedlings are cold-sensitive, whereas maturing plants are cold-tolerant. For optimal yield, rainfall should be over 350 mm during the growing period. L. luteus has the most modest water requirements (250 mm). Lupins are drought-resistant thanks to their deep roots, but are somewhat sensitive to moisture deficiency during the reproductive period. The best soils for lupin cultivation are well drained, neutral to acid loams. Growth is hampered on clayey and waterlogged soils, while highly calcareous or alkaline soils induce chlorosis and also reduce growth, frequently precluding cultivation. The accepted limiting soil level of CaCO3is 3-5 g/100 g for L. albus , 0.5-1 g/100 g for L. angustifolius and 0.5 g/100 g for L. luteus . The limestone tolerance of L. mutabilis is midway between those of L. albus and L. angustifolius . Some cultivars of L. albus are more tolerant of soil salinity than most crops.
Propagation and planting
Lupins require deep soil preparation in order to facilitate root growth. Sowing is done before or after the first rains in autumn in subtropical and warm-temperate regions and in early spring in cool-temperate regions. Early sowing favours growth. Shallow seeding (1-5 cm deep) is advisable. The recommended plant density per ha for sole cropping is 450 000-600 000 for L. angustifolius and L. luteus , 250 000-800 000 for L. albus and 200 000-400 000 for L. mutabilis . Lupins are often grown mixed with cereals and other fodder legumes. Inoculation with Rhizobium lupini is necessary prior to sowing in fields where lupins have not been cultivated during the last 4-7 years.
Cultivated lupins must be weeded, as they compete poorly with weeds during early growth. Pre-emergence herbicides are often advised. L. angustifolius and L. albus are mostly treated with simazine.
Lupins usually require no N fertilization, but soils containing less than 15 mg P/kg should be supplied with a phosphorus fertilizer at a rate of 30-120 kg P2O5/ha, while soils containing less than 40 mg K/kg should be fertilized with 50-120 kg K/ha. L. angustifolius is sensitive to magnesium deficiency, which can be corrected by applying 15-30 kg MgSO4/ha. Lupins should never be continuously grown on the same soil, but should be grown in rotation with cereals.
Lupin green manure gives the best yield of the subsequent crop when ploughed in at the grain filling stage. A green manure crop of L. albus in Parana (Brazil) had an effect equivalent to 80 kg N/ha and increased the yield of a subsequent maize crop by 25%. Even when lupins are grown for grain, they have a positive residual effect on the subsequent crops. In an experiment with L. angustifolius grown for grain in Australia, it yielded 2.5 t/ha, while the 2 following wheat crops yielded 5.4 and 4.7 t/ha, respectively. Three consecutive wheat crops yielded 4.0, 3.9 and 3.9 t/ha. The effect is attributed not only to residual nitrogen but also to a reduction of soil borne diseases. However, long-term use of lupins as green manure may lead to soil acidification.
Diseases and pests
Lupins are most commonly affected by brown leaf spot ( Pleiochaeta setosa ) and anthracnose ( Colletotrichum gloeosporioides ), and, to a somewhat lesser extent, root rot ( Fusarium , Pythium , the Rhizoctonia complex). The fungus Phomopsis leptostromiformis is a serious disease, as it produces a mycotoxin that causes lupinosis, a disease lethal to cattle and even more so to sheep; some lines resistant to this fungus are available now. The most widespread and harmful pests of lupins include army worms ( Heliothis spp.), which damage buds, flowers and pods. Phorbia platura attacks during germination and emergence, and results in plant losses, while the larvae of Sitona spp. severely damage root nodules.
The habit of lupins, with their rigid stem and high, non-shattering pods, facilitates mechanical harvesting for seed with a conventional cereal harvester. However, such a harvester may damage the seed, so threshing must be done very gently to avoid cracking. Accordingly, the lowest available drum speed and widest possible concave setting should be used.
The average dry matter production of lupins as forage or green manure amounts to 5-10 t/ha. L. albus and L. angustifolius grain yields can reach 6 t/ha. The typical average grain yield per ha is 1.5-3 t for L. albus , 1-2.5 t for L. angustifolius , 1.2-2 t for L. luteus and 0.75-2 t for L. mutabilis .
Handling after harvest
Lupin seed should be stored in a dry and cool place and does not require special storage conditions.
Germplasm collections of lupin are maintained at the Western Australia Department of Agriculture, South Perth, Australia; at Campex Semillas Baer, Temuco, Chile; and the Banco de Germoplasma Instituto Nacional de Investigaciones Agraria, Madrid, Spain.
Since ancient times, farmers have selected plants of L. albus and L. mutabilis with non-shattering pods and large white seeds that germinate rapidly. Sweet strains of L. luteus , L. angustifolius and L. albus with a low alkaloid content (0.02-0.05 g/100 g) became available in the first 30 years of the 20th Century. Subsequently, strains of L. luteus and L. angustifolius with non-shattering pods and permeable seeds were developed. Sweet strains of polygenic heredity were recently obtained in L. mutabilis .
The current aims of improvement for the Mediterranean region include complete removal of alkaloids, adaptation to winter and spring sowing, increased resistance to cold and diseases, reduced plant height and branching, higher yield levels, higher seed-protein content with more balanced amino acid composition. Selection in L. cosentinii Guss., L. pilosus L. and L. atlanticus Gladst. is currently being directed for use in soil improvement and forage production in clayey or alkaline soils.
Lupins have great potential for soil improvement, particularly in low rainfall areas with poor acid soils and low phosphate status. They are inexpensive sources of protein for livestock and humans. The wide variation in existing Lupinus species and their great ecological adaptability will allow expansion of growing area for various purposes including soil improvement, seed and forage production. Their use in South-East Asia will remain restricted to highland areas. Lupin development has lately been fostered by the establishment in 1980 of the International Lupin Association (Cordoba, Spain) to promote international cooperation and research on lupins.
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L. López-Bellido & M. Fuentes