Lupin

Lupin is grown mainly as a grain legume for its high-protein seed. Sweet, low-alkaloid cultivars are used in feed and, after processing, in human food, while the crop also serves as a nitrogen-fixing break crop on soils poorly suited to other legumes.

Species selection is important: narrow-leafed and yellow lupins are especially well adapted to acidic sandy soils, while white lupin is more demanding of fertility and moisture but can yield well on suitable land.

Family

Fabaceae (legume family)

Genus

Lupinus

Principal cultivated species

Lupinus albus (white), L. angustifolius (narrow-leafed), and L. luteus (yellow)

Root system

Deep taproot bearing nodules that host nitrogen-fixing rhizobia; some species form cluster roots that aid phosphorus uptake

Old World lupins, including white and yellow lupin, have been cultivated around the Mediterranean since antiquity, while narrow-leafed lupin is an important modern grain crop in Australia and parts of Europe. A separate lupin, the Andean tarwi, was domesticated in South America.

Lupins are cool- to temperate-season crops. In Mediterranean and mild-winter regions they are autumn-sown and grow through the cooler months, while in cooler regions they are spring-sown. They are sensitive to heat and drought during flowering and pod fill.

Species differ in frost tolerance and season length, which, along with soil type, guides the choice of species and cultivar for a given environment.

Lupins are distinctive among legumes for thriving on acidic, sandy, and low-fertility soils. They are, however, sensitive to alkaline and calcareous soils, where lime-induced chlorosis and poor growth occur, and to waterlogging.

Lupin is direct-seeded into a firm seedbed, with species and sowing time chosen to match soil and climate. Because early growth can be slow, weed control during establishment is important, and the crop is commonly grown in rotation with cereals.

• Species selection matched to soil acidity, texture, and season length
• Sowing time (autumn or spring) matched to regional climate and frost risk
• Weed management during early establishment
• Rhizobial inoculation with lupin-specific strains in fields new to the crop

Lupins fix substantial nitrogen through effective nodulation and can leave a strong residual benefit for following crops. Some species, notably white lupin, form cluster roots that release organic acids and improve access to sparingly soluble phosphorus.

Lupins are grown mainly under rain-fed conditions in temperate and Mediterranean regions. Yield is sensitive to moisture stress during flowering and pod fill, and the crop is intolerant of waterlogging on the light soils it commonly occupies.

On sandy soils with limited water-holding capacity, seasonal rainfall distribution is a key determinant of yield.

Anthracnose is a serious, seed-borne disease of lupins that can devastate susceptible crops, and sclerotinia stem rot causes losses under cool, moist conditions. Root rots and other fungal diseases occur where drainage is poor.

Aphids are important pests, both directly and as virus vectors, and thrips and other sap feeders also affect the crop. Management combines clean, disease-free seed, resistant cultivars, rotation, monitoring, and, where warranted, locally authorized controls applied according to their labels.

Grain lupin is harvested by combine once pods and stems have dried and the seed has reached a moisture content suitable for storage. Some species and cultivars are prone to pod shattering, so harvest timing and cultivar choice help limit losses.

• High-protein seed used as animal feed, particularly for ruminants and other livestock
• Sweet, low-alkaloid seed used in human food and food ingredients after processing
• Traditional bitter lupini beans debittered before eating in Mediterranean cuisines
• Use as a nitrogen-fixing break crop and green manure on light, acidic soils